Stay where you are if
Fax traffic, a live contract and the alarm panel, lift phone or card terminal sharing that pair are on the main VoIP guide. Any of them is a reason to leave things alone.
- The connection at the address is the whole question. Out where the nearest town is a drive rather than a turn, a link can be fine for email and still deliver a call in pieces. Test it from the building, at your busiest hour.