Voice Over Internet Protocol
I have that with orange (formerly wanadoo), u take your ordinary landline phone from your BT socket and plug it into your router then activate your wireless and talk service, it works just the same way as it would in the BT socket only, instead of using your BT landline your using your internet service provider. I get free call’s to all UK landlines 24/7 for upto 2 hour’s per call.