So in English:
SOGEA means Single Order Generic Ethernet Access. It describes a
landline which carries ADSL or VDSL but is not linked to a phone number.
So first, set up an account with your preferred VoIP provider. Ask them
how best to proceed.
They will probably suggest asking your existing VDSL provider to convert
the service to SOGEA. Warn the VoIP provider the date on which this
conversion will take place and tell them your landline phone number, so
that they are prepared to import that number. In the past this was not
possible - any change to SOGEA cancelled the landline number, but since
Easter this year OFCOM has insisted that cancelled landline numbers be
available for transfer to a new service provider for 30 days.
Experience of other people here is that this process still can fail,
particularly if the releasing service provider is an organisation as
incompetent as Vodafone.
So you might simply wait.
At some point in the next 10 years your VDSL will be converted to fibre.
Your existing ISP may then offer an ultimatum:
a) have new FTTP but no landline number
b) have new FTTP with their proprietary "Digital Voice" VoIP service
So make your decision.
If you have a landline that does not support any of VDSL, ADSL or
dial-up then you are unlikely to ever get any sort of digital service.
It probably means you can't get 3G, 4G or 5G mobile either, because of
your geographical location. So talk to BT and ask them what will happen
when all copper landlines are withdrawn and see what they will commit to
for the future.
--
Graham J