The regulation agencies and telcos in Ireland tend to call it PSTN (Public Switched Telephone Network) service when referring to normal phone service. POTS seems to be more of a casual way of describing it.
Terminology we use:
PSTN - Public Switched Telephone Network
ISDN - Integrated Services Digital Network
xDSL - Any form of Digital Subscriber Line service.
VoIP - Voice over Internet Protocol.
I realise that PSTN can also be used to describe the entire telephone network//
