SIP registration
A typical SIP network has a SIP proxy server and a SIP location server. (See Configuring SIP network components for more information.) The proxy server receives SIP INVITE messages for a domain. Its role is to route requests to the appropriate destination by communicating with the location server. The location server contains contact information for a specific SIP address.
When the Telephony Session service starts, it creates the first instance of the SIP audio provider and instantiates a SIP user agent. There is one SIP user agent per Telephony Session service. It handles all instances of the SIP audio provider for that Telephony Session service. All SIP user agents that want to be reached through a generic address must register themselves with the location server (via audio.sip.LocationServerURI). If a location server is not specified, then registration does not take place.
Registration occurs in the following situations:
- When the SIP user agent is created
- When registration has expired and the user agent registers itself again
The SIP audio provider supports Digest authentication as described in RFC 3261. In digest authentication, a proxy or location server challenges the request initiator to provide assurance of its identity. To enable this mechanism, use audio.sip.AuthRealmUseridPassword.
This example shows a typical message exchange after setting this service property. Assume that:
- audio.sip.LocationServerURI is set to vwg-lab1
- audio.sip.UserAgentURI is set to sip:user@nuance.com
- audio.sip.AuthRealmUseridPassword is set to nuance.com:user:abc123
The SIP audio provider (Telephony Session service) sends this message to the location server:
REGISTER sip:vwg-lab1 SIP/2.0
From: <sip:user@nuance.com>;tag=nu-675f-883c
To: sip:user@nuance.com
Contact: <sip:user@10.3.1.114:5060>;action=proxy;expires=60;transport=udp;q=1
Call-ID: 12758931151756707@dhcp-10-3-1-114.nuance.com
CSeq: 7282 REGISTER
Content-Length: 0
The proxy or location server challenges the request with a 401 Unauthorized response:
SIP/2.0 401 Unauthorized
From: <sip:user@nuance.com>;tag=nu-675f-883c
To: sip:user@nuance.com;tag=1114457599832-5938662
Call-ID: 12758931151756707@dhcp-10-3-1-114.nuance.com
CSeq: 7282 REGISTER
Content-Length: 0
Via: SIP/2.0/UDP 10.3.1.114:5060
WWW-Authenticate: Digest nonce="4d27d3724cd24af0dd202fb6d9d523f15b68bc30",
realm="nuance.com"
The SIP audio provider adds the credential information to the REGISTER message and sends it back again:
REGISTER sip:vwg-lab1 SIP/2.0
From: <sip:user@nuance.com>;tag=nu-675f-883c
To: sip:user@nuance.com
Contact: <sip:user@10.3.1.114:5060>;expires=60;action=proxy;transport=udp;q=1
Call-ID: 12758931151756707@dhcp-10-3-1-114.nuance.com
CSeq: 7283 REGISTER
Content-Length: 0
Via: SIP/2.0/UDP 10.3.1.114:5060
Authorization: Digest username="user",realm="nuance.com",nonce="4d27d3724cd24af0dd202fb6d9d523f15b68bc30",response="b86e6ca532321829618632caac250269",
uri="sip:vwg-lab1"
