Changes between Version 86 and Version 87 of FAQ

Timestamp:

Feb 23, 2010 8:54:02 AM (14 years ago)

Author:

bennylp

Comment:

--

FAQ

@@ -867 +867 @@
       pjsip_cfg()->regc.check_contact = PJ_FALSE;
       }}}
- When the strict check is disabled, the client registration session will calculate the expiration time (which determines whether it should treat the resposne as successful registration or unregistration) with the following rule instead:
+ When the strict check is disabled, the client registration session will calculate the expiration time (which determines whether it should treat the response as successful registration or unregistration) with the following rule instead:
     - it will skip the Contact headers and get the expiration time from the ''Expires'' header instead.
     - when ''Expires'' header is not present, it will get the value from the expires parameter of the Contact header, regardless of the URI specified in the Contact header
 
+
+=== I saw PJSIP sends multiple REGISTER requests, one unregistration and one registration. Why? === #reg02
+
+This feature is part of NAT traversal feature of PJSUA-LIB. It works by comparing the Contact URI that we use in the REGISTER request against the address and port that the server returns to us in the 200/OK response of REGISTER request. If the addresses are different, PJSUA-LIB would reconstruct a new Contact URI based on this address info, unregister the existing Contact, and simultaneously send a new registration with the new Contact URI.
+
+This feature is required when we're working with a RFC 3261 compliant servers, which would blindly (and correctly) send inbound requests to client's Contact URI.
+
+This feature can be disabled by setting [http://www.pjsip.org/pjsip/docs/html/structpjsua__acc__config.htm#22961bb72ea75f7ca7008464f081ca06 pjsua_acc_config.allow_contact_rewrite] to zero.
 
 === My machine has multiple NICs (multihomed) and PJSIP chooses the wrong IP interface === #multihomed