At the end of April 2024, multi-talented UK ISP A&A - Andrews & Arnold - is shutting down its SIP2SIM service.

Here’s the official announcement.

If you’re not familiar with the service, here’s how A&A described it:

Our SIP2SIM® service consists of a SIM card, which you put in an ordinary dumb mobile phone and it makes that phone appear as if it is a SIP extension (e.g. SIP phone) on a phone system of your choice.

Sure, you can use a SIP app on your phone to terminate and originate SIP traffic - Groundwire (non-FOSS) is good; Linphone (FOSS) is fine - but SIP2SIM meant that you could put the SIM into any phone, even the “dumbest” old phone, and it became a SIP endpoint.

In practice, the registration to your SIP server was coming not from the phone but from A&A’s servers, and A&A was handling the bit between the phone and its servers, via one of its suppliers.

But that was all behind the scenes (well, once you’d set it up). You just used your phone to make voice calls¹ as usual, and the traffic went via either A&A’s own SIP service, your SIP server, or a third party’s SIP server.

The user never needed to know that there was a SIP service in the mix.

If you didn’t need that, then SIP2SIM probably wasn’t of interest.

But if you did, then SIP2SIM was a service par excellence.

I used SIP2SIM so that I could have a “business phone”, with my “business line” on it.

I had hoped for a SIP2SIM eSIM. That would have been amazing.

I stopped it around the time the pandemic began, I think, when I ceased travelling. A SIP app on my phone and computer did the trick.

It was never going to get a massive number of users, IMHO. Most people don’t want a SIM card which can talk to a SIP server.

But for those who did, A&A catered for them.

And, despite it being a niche service, A&A catered for them at a very reasonable price: £5 + VAT for the SIM, just £2 + VAT /month to keep it active, and then £0.02 + VAT per minute for calls to or from the SIM.

And that’s what prompted me to write about its demise.

SIP2SIM typified what I love about small, geeky businesses. Businesses run by people who create something neat, and who make it available to others, even if the audience was only likely to be relatively few.

It is a shame to lose from the marketplace something which was simply so cool.

So useful.

So undeniably geekily niche and yet affordable.

It did one thing, very well.

Even if this iteration of SIP2SIM is closing (and perhaps SIP2SIMv3 will come back one day), here’s to more niche, geeky services from small businesses in the future.