I’ve got a working asterisk configuration for a Grandstream HT503. At least, it works at home. At work it fails with, "Got SIP response 503 “Service Unavailable” back from "
Looking at the SIP debugs, the thing that stands out is:
Sending to (no NAT)
Transmitting (no NAT) to
Sending to (NAT)
Reliably Transmitting (NAT) to
But there shouldn’t be any NAT at work either.
What’s making this decision to use NAT?
Hope someone can help,