Hello,

does anyone know why SIP Trunks & voice mail to email would stop working all of a sudden

I would assume it has something to do with the fire wall but the data company say that nothing has changed they keep pointing to the NEC

Just wondering where else to look

There are many reason why, the easiest is to confirm the system is on the LAN.

Anytime SIP trunks are involved you should have a tracer program like wire shark, this will eliminate a lot of heart ache.