It allows us to offer a SIM that works like a SIP device. No, it is not an app, and will work on any old GSM 2G or 3G or 4G phone, but the calls are passed each way as SIP to/from a SIP gateway/service as a registered device. This could be a mobile connected to a company or home SIP system (asterisk, freeswitch, FireBrick, whatever) or simply registered on a VoIP provider platform (including A&As VoIP).
The good news is that this is not quite the same as before. It works on O2, but will have roaming even in the UK, as well as outside the UK. Roaming in the UK is pretty unusual, but I have already used the test SIMs on vodafone and EE. It costs more, and confirming the details of costs is one of the things on which we are working now.
We think it will be around £10 for the SIM and £4/month, with normal UK calls in or out on O2 at 2p/min. Prices to be confirmed, and plus VAT. Any VoIP calls charged by VoIP provider on top of that obviously.
Texting via http posts each way, or linking to an A&A number, with normal text charges on top of something for the mobile leg which we expect around the 2p to 3p per text. To be confirmed.
Data is currently NAT, but unfiltered, and not even via a UK link! But we are working on getting this via an APN that will allow us to do L2TP like the data SIMs. No promises on that one.
Obviously it will be easy to have a simple landline number on a SIM using A&A VoIP with it, but the real killer is when you link in to a PABX. See this Facebook video for an example of what I am talking about here.
Assuming we go ahead with this we are looking at SIMs in January. I'll be working initially as a trial until we have documented the limitations of how it works exactly.
Update: Yes, I changed "will" to "may" for good reason - watch this space.
Update: This really is touch and go now - we'll see what happens.
Update: Not happening, at least for now - lets see how it goes next year.
Update: OK, watch this space. We are still working on this. Just taking longer than we expected.
Update: Very close to launching now.