It will be the same sort of thing. Log into the modem and see if the phone line number is present
- If no phone line is not there, then they have the serial number wrong or have the phone line incorrectly tagged in your account
- If the phone line is there, then the phone is not activated correctly on the network side and needs to be fixed by them
Both these cases are especially true if there is any sort of dialtone on the phone port.
Make sure your phone is connected to the phone one port of the modem too to check, It is possible that the house wiring is not connected tot he modem so any house jackpoints are dead, but the modem is fine.
Worst case is they raise a ticket to their Tier 2 support and the can log into the modem anyway and sort it out.