I think I understand at a fairly basic level how the Openreach & Plusnet relationships and equipment work for ADSL/FTTC wih Openreach providing local loop connections to the Exchange DSLAM and backhaul over their data trunks to Plusnet's network, which then provides the links to the wider internet.
Plusnet take over my phone service tomorrow (along with an upgrade to FTTC), and it occurred to me that I have no idea how that system will work, and I can't find any details online that seem to describe it.
I think I know how the existing voice system works, with (simplistically) a local exchange that offers dialtone and accepts the dialed number then connected to a network of trunk exchanges which route the call to to the local exchange at the far end - or hand it off to the mobile networks at interconnect points if its a mobile call. Call data for billing etc is generated at various points.
When I switch my Phone to Plusnet I can envisage three possibilities
a) Openreach own the whole system. Call routing continues as before and only billing and optional service controls switch from BT control to Plusnet.
b) Plusnet own a (one or more) voice switches that are interconnected with the BT voice switches in the same way as the mobile operators interconnect. Openreach route my calls from the local exchange to Plusnet's switching centre which then routes the call onwards to the dialled destination.
c) It is is actually just a VOIP service with Openreach digitising the call ( at the local exchange?) and handing the data stream off to Plusnet in the same way as they do the ADSL data streams.
Can anyone tell me, or point me to some documentation that describes the voice system. There is plenty on the detail of how the ADSL/FTTC systems work, but not a lot on voice.
Thanks
