1.32 Why does the Nokia S60 VoIP Release 3.0 product fail registration after receiving a ‘200 OK’ response from the registrar?
The Nokia S60 VoIP Release 3.0 product uses the pseudo-random username of the Contact URI for matching the sent and received contact(s). If the username part of the URI is changed or removed, the SIP registration of the Nokia S60 VoIP Release 3.0 product fails after the ‘200 OK’ response.
According to Nokia’s interpretation of the SIP RFC 3261, the registrar shall not modify the Contact URI sent in the response to the register request. When forwarding a request, for example, INVITE, some SIP servers write their own address to the Contact URI, instead of correctly inserting a Record-Route header. This also works with the Nokia S60 VoIP Release 3.0 product, but as for the REGISTER request the Contact has a different meaning and should not be touched.