In Summary (from the OP)
theibm:
The problem:
Immediately after the tower switch on the situation for some local mobile uses people has deteriorated rather than improve. Mainly that mobile voice services simply stopped working. When trying to make a call the phone hangs then simply disconnects after 15-30 seconds.
Identified issues relate to voice calling:
Whilst 4G data services and TXT'ing services work normally voice calls simply stop working in the vicinity of these towers unless your in possession of a compatible phone with your service providers software (known as VoLTE) installed.
Full disclosure - this doesn't and probably never will effect me but sounds like an issue that I think needs to be fixed.