useful correction from our earlier discussion, Twilio can legitimately send a non-Twilio

number as outbound caller ID after you verify ownership of it. Their current documentation

explicitly supports that for voice. UK calls are nevertheless subject to Ofcom's CLI

validity rules, so the number has to genuinely identify the caller and be dialable, which

your own landline number should satisfy when configured correctly. So I think our next

step should be to find UK providers offering actual SIM-based PBX mobile extensions, rather

than trying to bend ground wire into doing it. That could be considerably neater for

your site. Yes, alright, so we've still got two prongs to examine here. One is about having

the SIM-based PBX, as you say, but crucially I want it to connect to my own PBX, not to

a service provided by another company.

Thank you very much.