Integrated Access Device (IAD)
An integrated access device is customer equipment that combines data and voice services, typically giving traditional phone sockets on a broadband line.
What is Integrated Access Device (IAD)?
An IAD built into a home gateway converts VoIP to analogue phone ports ("POTS" ports), so ordinary phones can be used over a fibre or IP connection. This is how landline phones keep working as the UK moves from the PSTN to digital voice.