I was using the 3120 as part of a VOIP with a VOIP provider. Going back to my local cable company and will be using their 2 lines and a new phone system. Is the 3120 compatible with this non-voip system?
Re: Adtran 3120 for local cable comp phone service.
The 3120 has no FXO or FXS ports, so presumably you were using IP phones or an ATA (analog telephone adapter) to get POTS dial tone. As a rule, cable providers supply their own equipment with regular RJ-11 jacks for telephone service over cable.
You could continue to use the 3120 as a NAT-router/firewall/4-port switch behind the cable company's gear, but it likely won't be involved in the voice part of the network. To be sure, ask the cable company what they're providing.