There is, but it hasn't been used for a very long time. There is a Virgin socket, and that is the phone line .
Honestly, I don't want to be mucking around with sockets and cables, I'm totally useless at anything like that, I just thought someone may know the answer. If not, I'll just have to remain in the dark and hope that when I'm out or on holiday in the future, the answer isn't the worst case scenario of the alarm going off repeatedly. Ironically, I don't think the SMS thing is working anyway, as the number programmed in is probably obsolete. I did ask the original installler, but their answer was that the alarm simply can't be activated if the phone line is down. Nopw I know they are wrong. I know what happens when it goes down when the alarm isn't activated - the control panel beeps at me. I just don't know what happens if the line drops when the system is armed. I suspect the answer might be that the alarm goes off, and will repeatedly sound the siren until the system is disarmed, becuase it could be a burglar that has cut the phone line, but I don't know.