Multimedia SIP Registration - 503 Service Unavailable

This is an IP Office security issue. We don't have all the answers as to why a customer would receive a 503 Service Unavailable error when trying to register virtual handsets for Multimedia. The partner is primarily responsible and can raise a ticket with Avaya to move forward if no resolution is found.

Known causes:

Extension Number and Password are the Same

Historically this is not a problem, but there is a security setting that, if enabled, prevents any user with matching credentials (extension and password) from registering. This is the case with the below setting applied (found in Security Settings > General).

Best to just not have the password be the same as the extension.

TLS protocol is activated and/or media security is too high

These steps may be temporary to verify if they are the cause for the 503 error. If so, yet the customer needs to re-activate these security measures, they'll need to open a ticket with Avaya to determine how to allow the virtual handset(s) to register.

Disable TLS in System > LAN1 > VoIP.

Media security is found in System > VoIP Security. Try at a lower or disabled security level for testing.