Cheap Telephone Calls

This is my how-to guide for getting cheap (or free) phone calls from an iPhone. It will work in the UK on O2, and possibly other networks depending on their policies for handling VOIP traffic. And probably other smartphones (and iOS devices) albeit with different software and/or instructions.

This is my how-to guide for getting cheap (or free) phone calls from an iPhone. It will work in the UK on O2, and possibly other networks depending on their policies for handling VOIP traffic. Rumour has it, O2, Orange, 3, and Giffgaff permit VOIP traffic - Vodafone and T-Mobile block it.[source] And probably other smartphones (and IOS devices) albeit with different software and/or instructions.

Some home routers do not play nice with SIP even if you forward the ports. Take, for instance, the O2 Wireless Box II - you need to change settings using the CLI (terminal, not Web) interface to disable "SIP ALG". You only have to Google SIP ALG breaks SIP to see how widespread the problem is, created by a "hidden feature" designed to make SIP work through NAT. Because of this, and the fact you won't know if SIP will work without without needing to do anything (both with your home Wi-Fi and your mobile network), I have inserted the following section, SIP2SIP.

SIP2SIP

SIP2SIP is a nice little service. I created an account a day ago (on 2013-01-15). It is a free service with no support, but you can top-up your account for extra features like calling PSTN numbers. You do this by purchasing $20 (+21% VAT, so $24.20) using a VISA, MasterCard, Discover, or AmEx credit card (note: I use the free account so can't comment on this process). Calls to UK 01/02 numbers are (at the time of writing) 0.8 cents/minute; 03 numbers 1.09 cents/minute; 0843, 0844, 0845, 0870, 0871, 0872, and 0873 numbers 56.51 cents/minute; Vodafone, T-Mobile, Orange, O2, and Hutchison 3G OFCOM allocated mobile numbers 4.56 cents/minute; other mobile networks 21.70 cents/minute; 0800, 0808, and 0500 numbers 1.02 cents/minute; 076 and 070 numbers 4.5208 dollars/minute; and 055 and 056 VOIP ranges 0.89 cents/minute. A quick currency conversion by Google, the prices for UK landlines and major mobile networks do seem pretty good - on par with Localphone at current exchange rates. No phone number is supplied or purchasable, but if you add credit you can open a support ticket to have caller ID setup for when you make calls over PSTN.

Anyway, when you create an account your username at sip2sip.info is your SIP-URI address. You can also add aliases (and delete them by deleting the text and saving aliases) from the Identity section after logging in, so your username doesn't have to be the SIP-URI you hand out.

Depending on your SIP client, you may have more or less features available to you. I am going to concentrate mainly on dialling SIP-URIs, but SIP SIMPLE text messaging, XMPP gateway, file transfers, etc. may be available to you too. One feature I particularly like with SIP2SIP is their website's call history log - click on Trace next to a call you've made and it should give you enough details to diagnose any problems in calls that connected.

The Software, Plus Setup Instructions

Unlike in the rest of this article, I am going to use a free app here. It would be rather pointless advising you what I think the best app is and what SIP providers I like without knowing if you're going to have some issues. So, the free app I have chosen is... Dialer+ SIP Voip Softphone by Tao Wang. Available for iPhone, iPod Touch, and iPad. Requires iOS 4.0+.

  • Click OK when asked if you want to add an account. Alternatively, click Settings, plus symbol.
  • You want to Add General SIP Account.
  • Name: Displayed to people you call. User Name: SIP2SIP Username (not the SIP Address). Password: your SIP2SIP Password. Domain: sip2sip.info. Description: SIP2SIP. Click Advanced.
  • Encrypt Audio: If Possible. Use Proxy: On. Proxy Host: proxy.sipthor.net. Realm: sip2sip.info. Go back to Settings. Account Enabled: On. Go Back, and back to Settings.
  • Go to Phone Settings. I have changed: Keypad Sound Volume (Low), Cellular button (Off), By GSM when failed (Off), When Missed (Off), and, Ringtone (dd).
  • Back to Settings, Media, WiFi Codec. I have all enabled except G.729, in the order: g729, g711a, g711u, g722, speex 32k, iLBC, GSM, speex 16k, speex 8k.
  • Back to Media, 3G Codec. I have (in order): g729 (Off), iLBC (on), GSM (On), and speex 8k (On). The rest are turned off.
  • Back to Media, back to Settings, Network Settings.
  • I have turned On: Enable uPNP, VoIP over EDGE/3G, Enable ICE. I have turned Off Test Net Speed (at least for present).

Making a Test Call

  • Click Keypad.
  • Dial 3333, you should hear some music
  • Dial 4444, you should hear your voice echoed back.
  • Click ABC near the top right, and type echo@iptel.org then press Call, you should hear your voice echoed back.

Can You Use SIP?

At this point, you should now know whether or not you are able to make SIP calls. If you cannot, see if your router can be made to work, or your mobile network requires something added to your contract (or if they block it, the cost of exiting your contract).

You might want to stop here if calling SIP-URIs, UK landlines and major UK mobile networks cheaply is all you want to do. Add credit to SIP2SIP, find out what their PSTN call quality is like, ignore the rest of this article.

If you want more features like call recording and push notifications for calls, the ability to use whichever of your SIP accounts is cheapest for a call automatically (after setting up some rules), and an iNum and geographical number (both for free), continue reading.

Cashback Sites

If you are not already registered with topcashback.co.uk, please consider using this referral link (delete cookies first - I usually switch to a different browser and delete its cookies so I'm not logged out of sites I have open in my preferred browser): https://www.topcashback.co.uk/ref/watfordjc

By registering with Topcashback, you will get £10.10 cash back (will become payable after approximately 90 days) from Localphone and if you used my referral link I will get £10 for referring someone who has earned at least £10 of cash back that has reached payable status.

If you would rather not register with a cash back site, consider using my Localphone referral link instead (again, wipe cookies and cache first): https://www.localphone.com/?rb=ELGNTGmZHJplFuGxsUhPliU_HasyqoOAOinl7UfItls and/or enter my e-mail address when you sign up.

Hint: my e-mail address is my twitter username without the @, this web address between the www. and the .com, or my username pretty much everywhere on public Web sites, followed by @googlemail.com

Hint 2: If you perform a WHOIS on my domain, my e-mail address is listed for the Administrative Contact.

Localphone

When/after you register for Localphone, I suggest you pick a free INUM (Internet Number) as it will allow other Localphone users, Google Talk users, and others to call you for free, Skype and others to call you at local rates, and some to call you at premium rates (last I checked, 60p/min from BT landlines, £4/min from BT pay phones).

To add a DID (Direct Inward Dialling) number, login to Localphone, go to My Account, go to Services, click on Incoming Numbers, and choose the country you want a number for, such as "International (iNum)". Click continue, check the setup and monthly fee (£0, £0 for INUM), click Select, read what is going to happen, and then click Purchase.

Once your number has been processed, go to Incoming Numbers again and click Manage Number next to your new number. Make sure you are forwarding to Internet Phone (you may also forward to landline/mobile or Localphone Voicemail, you need to set-up a PIN to use Voicemail).

Some networks are not currently able to connect to the ITU-assigned +883 country dialling code (International Networks), area code 5100 (INUM/Internet Numbers) including O2. Don't worry - a free regular landline number will be set-up when you register with a different provider later on in this how-to.

After registering with Localphone, you'll need some pre-pay credit in your account (skip ahead to The Software if you want to make that test call first). Check on Topcashback to see if there are any codes for extra (bonus) credit on your first order (at the time of writing there were 2: 100% up to £5, or 10% - the former being the better deal unless you are adding more than £50 credit).

Note that VAT at 20% is added at the checkout, and that the top-up amounts are in £1 increments (minimum £1). Next to VAT, you can click a link that switches the amount of £x to include/exclude VAT. Next to Total, you can click a link that allows you to enter any amount of £1 or more (whole pounds only).

The Software

You can use the free App from Localphone, but I recommend purchasing Groundwire (or Acrobits if you don't think you'll ever use the additional features). Check if Topcashback has cash back for Apple, at the time of writing if you clicked through to the App Store from Topcashback, you'd get 5.05% cash back - Groundwire costs £6.99, Acrobits £4.99.

Setting Up Groundwire

At this point, you should have a Localphone account, and a SIP client installed on your smartphone. I am going to use Groundwire here as it is the one I prefer out of the several I have tried.

  • Fire up Groundwire.
  • Click Settings (from the Keypad tab) and click Incoming Calls.
  • Which you choose here will be the global default in Groundwire. Push notifications does require sharing your Localphone SIP details (different to your Localphone website login details) with a push server (over HTTPS), so there is the possibility someone could drain the credit from your account if the push server is compromised or several other things occurring (such as a rogue certificate authority issuing a certificate that allows someone to launch a Man-In-The-Middle attack. Given that push notifications are the more reliable option, that I never have a massive amount of credit in my account, the fact the SIP details would not allow someone to take over my phone number or account, and the unlikely (though not improbable) case of compromise, I use push notifications. You also have full itemisation in your Localphone account including incoming and missed calls.
  • Go back to Settings.
  • Select Preferences.
  • For Ringtones, you have one for when Groundwire is the active application and your phone is not locked, one for Push (cannot use media library tunes for that) and a Text Tone.
  • Under Sound are some options such as Bluetooth support, echo and noise suppression, and volume boosting.
  • Under call recording you can customise call recording options. Check the legal situation in your country - in the UK it is OK to record calls for your personal private use, but there are laws saying what is and is not OK.
  • Tap Number Rewriting, plus symbol, plus a condition of Starts With 00, Done, plus an Action of Replace with +, Done, back to Number Rewriting. Plus symbol, plus a condition of Starts With 0, Done, plus an Action of Replace With +44, Done, back to Number Rewriting, back to Preferences.
  • Under Controls there are a lot of customisation options, none of which I have changed IIRC.
  • 3G/Wi-Fi Selection - in most cases you'll want Prefer Wi-Fi, although if your broadband is flakey at present, or you have something like BT Fon installed and you don't plan on stopping when you receive a call through that hotspot you are walking past, you might need to know where this setting is.
  • Go back to Settings, and tap Add-Ons. These are the In-App purchases available. G729a is good for lowering bandwidth used when using 3G/EDGE, ZRTP is encryption that I'm not sure Localphone supports. NAT Bridge should not be needed in most cases.
  • Go back to Settings.

Adding Your Localphone Account to Groundwire

  • Click on SIP Accounts, then click the plus symbol.
  • Wait for the SIP providers to load, then in the Search box type Loc and tap Localphone.
  • On your computer, other device, or web browser on your device, login to the Localphone website.
  • Go to My Account, Settings, Internet Phone.
  • Scroll down to the "Call from your VoIP box"
  • In Groundwire, your username is the SIP ID and your password is the SIP Password.
  • Click Done and Save.
  • Back in SIP Accounts, click the arrow next to Localphone.
  • Display Name is what may be shown to the recipient of a call made to a SIP URI.
  • Go to Advanced Settings.
  • For Proxy, enter proxy.localphone.com
  • Go to Codecs fo WiFi.
  • I prefer the order G711u, G711a, G722, G729a (requires In-App purchase), iLBC, GSM. Other codecs disabled.
  • Honour Remote Codecs... That's up to you.
  • Back to Advanced Settings, and to Codecs for 3G.
  • Here I prefer the order G729a, iLBC, GSM. Other codecs disabled.
  • Honour Remote Codecs... Off is best if you want your codec order to be followed strictly.
  • Back to Advanced Settings and into Secure Calls.
  • SDES is up to you.
  • ZRTP - Enable for incoming unless you experience a problem. This allows you to honour someone's preference of making calls securely.
  • Back to Advanced Settings, Done, Settings, Done.
  • Note: Do not fill in Caller ID as it may prevent you from registering or making calls. Instead, go to the Localphone Web page with the "Call from your VoIP box" and near the bottom of the page is a link to set caller ID options. You can add any numbers (such as your mobile) but you need to confirm you own it by answering an automated call and entering a PIN read out/displayed, and you need to visit the web site each time you want to switch caller ID.

Making a Test Call

  • Click the phone icon in the top left of Groundwire.
  • Select Localphone as the dial-out account.
  • Call the BT News Freephone Number: 0800500005.
  • Check it connects and you can hear it.

Other Tests to Conduct

  • Make a call over Wi-Fi, can both parties hear each other and can they hear keypad tones OK?
  • Receive a call over Wi-Fi, can both parties hear each other?
  • Make a call over 3G, can both parties hear each other and can they hear keypad tones OK?
  • Receive a call over 3G, can both parties hear each other?
  • Make a test call to a SIP URI (click the box where the number usually appears, and use the keyboard to tap in the address). Call echo@iptel.org (an echo service like Skype's) - can you hear your voice echoed back to you?

Cost of Making and Receiving Calls over 3G

These are the figures I got from the Web (using Layer2 overhead):

  • G711 (64 kbps, 20 ms voice payload size) - 168 kbps
  • G722 (64 kbps, 20 ms voice payload size) - 168 kbps
  • GSM (13.3 kbps, 20 ms voice payload size) - 61.32 kbps
  • iLBC (15.2 kbps, 20 ms voice payload size) - 61.32 kbps
  • iLBC (13.33 kbps, 30 ms voice payload size) - 61.32 kbps
  • G729a (8 kbps, 10 ms voice payload size) - 50.4 kbps

These figures assume the maximum in both directions, and things like noise suppression turned off. You can probably halve these figures.

Most networks charge for data by the MegaByte, so I am going to convert the above to seconds per MB and MiB:

  • G711 - 48.7 s/MiB, 47.6 s/MB
  • G722 - 48.7 s/MiB, 47.6 s/MB
  • GSM - 133.5 s/MiB, 130.46 s/MB
  • iLBC 20/30 - 133.5 s/MiB, 130.46 s/MB
  • G729a - 162.5 s/MiB, 158.7 s/MB

If you buy a data bundle, this is how many minutes you'll get:

  • G711 and G722 - 20 min/25 MiB, 19 min/25 MB
  • GSM and iLBC - 55 min/25 MiB, 54 min/25 MiB
  • G729a - 67 min/25 MiB, 66 min/25 MB

Again, if you use noise suppression and aren't both talking simultaneously, you can probably at least double those figures.

O2 PAYG allows 50 MiB for a £1 daily cap. Plugging in the figures and using Localphone's H3G/O2/Orange/T-Mobile/Vodafone rate of 4.8 pence/min:

  • G711 and G722 - 40 minutes for £1 data and £1.92 calls.
  • GSM and iLBC - 110 minutes for £1 data and £5.28 calls.
  • G729a - 134 minutes for £1 data and £6.44 calls.

The 100 MiB data bundle:

  • G711 and G722 - 160 minutes for £3, plus call charges.
  • GSM and iLBC - 440 minutes for £3, plus call charges.
  • G729a - 536 minutes for £3, plus call charges.

So, 500 any (major) network minutes equivalent per month using G729a (£6.99 one-off In-App upgrade purchase) will cost £27.

Bear in mind though that unlike with mobile contracts that come with "free minutes", your calls to landlines (or Freephone numbers, or SIP URIs, or Localphone numbers, or INUM numbers) will not be deducted from your minutes. If 60 of your minutes are to 01/02/03 numbers, at 0.5 pence/min you've dropped down to £21.42 a month.

Calls to 0845 (9.8 pence/min) is a lot pricier than calling 0870 (4.9 pence/min). This is where Sipgate.co.uk comes in - a free geographical number, and you get calls to 0845 numbers for 3 pence/min at all times.

I have just found netSIP who, at the time of writing, charge 2.352 pence/min to (from the look of it) OFCOM's mobile (074/075/077/078/079) allocations for Hutchison 3G UK Ltd, Lycamobile UK Limited, Vodafone Ltd, Orange, Everything Everywhere Limited (TM), and Telefonica UK Limited. Calls to other mobiles at 9.408 pence/min (more expensive) and personal numbers (070 and some 076) at 12.642 pence/min. Their 084, 0871, and 0872 prices are also more expensive at 13.132 pence/min and 0845 at 7.644 pence/min, but their 0870 charges are just 1.764 pence/min. I will test them for a while, and will add instructions for using them at a later date. netSIP instructions added below.

Oh, you also now have the capability of whipping out your mobile when you need to call a US 1-800 or 1-888 number - do it when connected to Wi-Fi and it won't cost you a thing, on 3G it'll use a bit of data. Spain landlines? 1 pence/min. US landlines/mobiles? 0.5 pence/min. Canada, Cyprus, France landlines? 0.5 pence/min. 00800 numbers - free (or a bit of data).

If you get the £10.10 cash back from Topcashback for Localphone, the 28 pence cash back for Groundwire, and used the 100% bonus credit code for £10 Localphone credit, and purchased the G729a Add-on for £6.99, you have spent £23.98, have £18.00 of VAT-inclusive credit, and will get £10.38 cash back in a few months. That comes to... -£4.40 you will have spent in total (see, that's sort of "free"). I'll get a tenner too if you weren't already a member of Topcashback and used me as a referrer.

If you just switch to making landline calls using Localphone and Groundwire, that's 200 anytime minutes for £1 a month (plus data charges). People can call your mobile for the cost of data (you also pay as you use data to receive calls too). You have a landline number with you without (at present) any charges or BT line rental (I will at some point add the instructions for setting up sipgate.co.uk, it is similar). Instructions for sipgate.co.uk added below.

Those minutes you pay for each month can be used for those more expensive calls.

That PAYG tariff has become redundant. I have spent a total of £4.63 on calls - and £6 on data, but I use data a lot - in the last 3 months, a total of 95 minutes of calls, including (rounded up for per minute billing): 50 minutes to mobiles (alone would have cost me £12.50), 15 minutes to US Freephone numbers (that's another £22.50), and 32 minutes to 0845 numbers (another £8.75), plus the calls to landlines. I haven't really saved £39.12 though as I previously wouldn't have made any calls. Had I used 18185 to make those 0845 calls like I used to, it would have cost me 5 connection fees (25 pence) more.

Sipgate

  • Visit sipgate.co.uk and register for a "sipgate basic residential VoIP" account.
  • You are asked for your country and area code. This will be used on the next page for your (currently) free geographical number. There is a chance no number is available for that area code if someone else has recently added one to their account. As with those outside the UK (according to their IP address and Sipgate's geo-location software) you'll be offered a choice to use an 0845 or 0870 number instead. What I would suggest is check back in a couple of days for one in your preferred area code, or choose a different area code (note: there appears to be the option to change your number later). As for picking between 0870 and 0845, I would probably pick 0870 because it is possible to find a cheaper way to call 0870 than 0845 using SIP or calling card providers, and at least for my O2 PAYG plan and 18185 go, they are charged the same rate (and 0870 is cheaper than 0845 at weekends using 18185).
  • After the pre-selection list, confirming the number you would like, and going to te next page, fill in all your details and read the agreement.
  • You are done, just need to wait for the e-mail(s).

Adding Your sipgate.co.uk Account to Groundwire

  • Click on SIP Accounts, then click the plus symbol.
  • Wait for the SIP providers to load, then in the Search box type sip and tap sipgate.co.uk.
  • On your computer, other device, or web browser on your device, login to the Sipgate.co.uk website.
  • Go to Settings, Overview.
  • Scroll down to the "SIP account data" section.
  • In Groundwire, your username is the SIP-ID and your password is the SIP password.
  • Click Done and Save.
  • Back in SIP Accounts, click the arrow next to sipgate.co.uk.
  • Display Name is what may be shown to the recipient of a call made to a SIP URI.
  • Go to Advanced Settings.
  • For Proxy, enter sipgate.co.uk
  • Go to Codecs fo WiFi.
  • I prefer the order G711u, G711a, G722, G729a (requires In-App purchase), iLBC, GSM. Other codecs disabled.
  • Honour Remote Codecs... That's up to you.
  • Back to Advanced Settings, and to Codecs for 3G.
  • Here I prefer the order G729a, iLBC, GSM. Other codecs disabled.
  • Honour Remote Codecs... Off is best if you want your codec order to be followed strictly.
  • Back to Advanced Settings and into Secure Calls.
  • SDES is up to you.
  • ZRTP - Enable for incoming unless you experience a problem. This allows you to honour someone's preference of making calls securely.
  • Back to Advanced Settings, Done, Settings, Done.

Making a Test Call

  • Click the phone icon in the top left of Groundwire.
  • Select sipgate.co.uk as the dial-out account.
  • Call the Sipgate test number - 10000.
  • Check it connects and you can hear the message.

Add Funds to sipgate.co.uk Account

10000 occasionally doesn't work for anyone, so you may want to add money to your account and do the same tests as you did for Localphone.

To top-up your account, go to Billing, Credit your account. Sipgate.co.uk accept VISA, MasterCard, and AmEx credit cards (I assume VISA Debit works, can't remember). Unlike Localphone, Sipgate.co.uk only have top-up values of £10, £20, and £50 - if you want £1 or £25, you can't.

netSIP

Registration with netSIP is not that simple.

First, you need to register at netSIP.co.uk. Enter your name, address, post code, e-mail (check it is correct, otherwise you won't get your login details), contact number (feel free to use your Localphone number), and the captcha.

When you click submit, you will get your non-working login details. Do not try to login yet, you need to credit your account first.

Click on Buy Credit. Enter your User ID (i.e. NSxxxxx where x is a number), and choose from £10, £20, or £50 (not as flexible as Localphone either). Cheque and Online Bank Transfer do not have a handling charge, Paypal and Credit/Debit Card do.

If you choose Online Bank Transfer you will need to create a new Payee using your bank's online banking, so may need that telephone number your bank has on record or that thing you put your debit card in and key in a code (or whatever method of multi-factor authentication they use). Don't forget to use your User ID (NSxxxxx) as the reference!

If you chose cheque, you need to enter the cheque details in the "Notes to netSIP" box, as well as write some stuff on the back (and front, obviously) of your cheque.

Check the instructions for your method of payment in the "Payment Method Instructions" box. If you clicked "Pay Now with Paypal", pay now with Paypal. If you clicked Submit, you need to arrange payment. In the case of cheques, you need to contact netSIP before sending it. In the case of Online Bank Transfer, you need to send the amount you selected to the payee you set-up in online banking. Make sure your User ID is correctly entered as the payee reference (or whatever your bank calls it) and the amount is what you chose when creating the payment order at netSIP. Send the money (yes, netSIP are Faster Payments enabled).

Once your payment has been processed, you will receive an e-mail confirming your purchase. You should now be able to login to your account - your Username is probably different/longer than your User ID.

Adding Your netSIP Account to Groundwire

  • Click on SIP Accounts, then click the plus symbol.
  • Click Generic SIP Account
  • Open your e-mail with your netSIP login details.
  • In Groundwire, Title is netSIP, Username is your netSIP User ID (e.g. NS0000*netSIP) and Password is your netSIP Password. Domain is sip.netsip.co.uk
  • Click Done and Save.
  • Back in SIP Accounts, click the arrow next to netSIP.
  • Display Name is what may be shown to the recipient of a call made to a SIP URI.
  • Go to Advanced Settings.
  • For Proxy, enter sip.netsip.co.uk
  • Go to Codecs fo WiFi.
  • I prefer the order G711u, G711a, G722, G729a (requires In-App purchase), iLBC, GSM. Other codecs disabled.
  • Honour Remote Codecs... That's up to you.
  • Back to Advanced Settings, and to Codecs for 3G.
  • Here I prefer the order G729a, iLBC, GSM. Other codecs disabled.
  • Honour Remote Codecs... Off is best if you want your codec order to be followed strictly.
  • Back to Advanced Settings.
  • For Auth User Name, use your netSIP User ID (e.g. NS0000*netSIP), and for Transport Protocol use udp.
  • Go into Secure Calls.
  • SDES is up to you.
  • ZRTP - Enable for incoming unless you experience a problem. This allows you to honour someone's preference of making calls securely.
  • Back to Advanced Settings, Done, Settings, Done.

Making a Test Call, Changing Password, and changing Caller ID

Make a test call (or calls) following the instructions above for Localphone.

To change your netSIP password, login to their website, go to Tools and Settings, Change Password, then enter your supplied password and your new one. Once successful, change your netSIP password in Groundwire.

To change your caller ID, go to Tools and Settings, SIP Settings. Enter it following the E164 Standard (e.g. +442079460202). Click apply. Note: At the time of writing entering an INUM number for caller ID caused a problem in which all outgoing calls reported a busy signal. I have reported it as a bug and am awaiting a response. "At the moment our servers are not supporting or sending iNum Caller ID. We are working on it. Will update you soon."

Caller ID

You may want to have the same caller ID across all your SIP accounts. Unfortunately, sipgate.co.uk only allow you to use a number supplied by them. So, that geographical number you set up earlier can be added to both Localphone and (if applicable) netSIP, and when calling the majority of people with CLID (or 1471) you will appear to be using the same number no matter which Dial-Out account you're using.

Choosing the Cheapest Dial-Out Account

The top-left of Groundwire displays the SIP account that would be used if you made a call right now. Click it, and you can switch between it and any others you have set up.

Generally, use Localphone for all calls except 0844 and 0845 numbers, where sipgate.co.uk is cheaper. If you add netSIP to your choices, use them for calling UK mobiles and 0870 numbers. For 080/050 numbers, use either sipgate.co.uk or Localphone for 0 pence/min, and for INUM (+8835100) numbers use Localphone for 0 pence/min. Use sipgate.co.uk for sipgate and 00800 numbers, and Localphone for Localphone numbers.

At home I have a Raspberry Pi with, among other things, Asterisk and FreePBX installed. As well as SIP Trunks from Localphone, sipgate.co.uk, and netSIP set up, I also have dialling plans and rules and time ranges for when each is permitted. When I finally get around to reporting my line fault and getting rid of all that crackling, I will consider adding something like a SPA3102 so I can route calls through my Post Office Home Phone line when it is cheaper/free (e.g. Evenings and mobiles at weekends).

If I'm at home or using Wi-Fi that I know doesn't need the use of a proxy, I just use my home SIP account and the cheapest SIP provider (for the calls I have allowed) is automatically used, as are ENUM lookups for free SIP-URI dialling. I also have a SIP-URI that can be dialled wherever I am. The only trouble is when one-way-audio occurs and a proxy is needed, but that does seem to only be a problem for outgoing calls (the reason I don't have just one SIP account in Groundwire). If I were to make calls to SIP-URI addresses when out and about, I would give Groundwire's 69 pence/month NAT Bridge Monthly Add-On a try to see if it works for SIP-URI calls.

I have just discovered Groundwire's Number Rewriting is more powerful than I thought. I will add some details about using Number Rewriting to Override Dial-Out Account at a later time. Note that the Number Rewriting rule setup earlier means all numbers should be in E164 format, so overriding 0870 numbers to use netSIP you'll want to add a Condition in netSIP's Advanced Settings, Number Rewriting, of +44870, and an Action of Override Dial-Out Account.

Your SIP-URI

If you followed the instructions on this page, you now have a couple SIP URIs that anyone in the world can use to call you for free (plus data costs at both ends):

  • +8835100xxxxxxxx@localphone.com (and 8835100xxxxxxxx@localphone.com)
  • username@sip2sip.info

What I suggest you do, is edit your own contact in your iPhone, go down to the web addresses, click the label next to the blank one, scroll down to add custom label, enter SIP-URI, and then add the following as SIP-URI addresses to your contact details:

  • sip:8835100xxxxxxxx@localphone.com
  • asoftphone:8835100xxxxxxxx@localphone.com
  • groundwire:8835100xxxxxxxx@localphone.com
  • sip:username@sip2sip.info
  • asoftphone:username@sip2sip.info
  • groundwire:username@sip2sip.info

And now share it with whomever you choose. The whole "what phone company is that number with?" thing has just disappeared, and anyone with a SIP client and SIP provider can now call you for free.

The only problem now though is that not all SIP providers permit "anonymous" SIP calls. If you try to return a call to a sipgate.co.uk SIP-URI and aren't registered with sipgate.co.uk (nor have sipgate.co.uk selected as your Dial-Out), you'll get a busy signal, forbidden, or other error.

Unfortunately, Groundwire does not appear to offer a way to create a group of settings for just SIP-URI dialling. Localphone seems to corrupt SIP-URI calls. Selecting sipgate.co.uk or netSIP for Dial-Out when calling a SIP-URI seems to work fine, however, the person you are calling will not be able to return the call unless you called them with sipgate.co.uk as your Dial-Out and they select sipgate.co.uk as their Dial-Out (presumably because the sipgate.co.uk settings give the Username as Caller ID and sipgate.co.uk considers a 7 digit phone number as a sipgate.co.uk user). Whether there is a way to get around this, I am yet to find out.

I suppose one workaround would be to create a sipgate.co.uk label in your iPhone and add a telephone number with that label to your contact entry for yourself, with the phone number as your sipgate.co.uk ID. Make SIP-URI calls with your Dial-Out as sipgate.co.uk and it will appear to anyone you've sent your contact details to as Your Name and sipgate.co.uk underneath in their call history. Since they can change the Dial-Out from Groundwire's History page, or add a Dial-Out Override rule to sipgate.co.uk for all numbers with a length of 7, it should make returning SIP-URI calls at least possible without setting up your own SIP-compatible PBX or paying a company for one. Hopefully you don't have 7-digit long numbers stored in your phone?

This article will be formatted at a later time. Article formatted on 2013-01-12, also edited to add my Localphone referral link. Added details of mobile providers that might be SIP-friendly, echo test using SIP-URI, mention of netSIP being cheaper for mobiles and 0870, 2013-01-13. Added Sipgate.co.uk and netSIP details, as well as some further information that isn't inside <ins> tags on 2013-01-14. Added mention of Numer Rewriting on 2013-01-15. Added details for SIP2SIP, and a bit about SIP ALG issues on 2013-01-16.