I have a Grandstream HL503 with a PSTN line connected to the FXO port. I want it to route incoming calls to an internal extension 300.
Under the Grandstream HL503 I have configured in basic settings:
Unconditional Call Forward to VOIP: my freepxb server and the trunk I have created.
The FX0 port is registered.
when calling the PSTN number I get the error: