[SR-Users] Why does Kamailio return many Contacts in Contact header in REGISTER response ?

When I make REGISTER request to server Kamailio. Kamailio sometimes return me REGISTER 200 OK response with many Contacts in Contact header field Contact: <sip:user1@1.1.1.1:58492 ;transport=TLS;ob>;expires=29;received="sip:1.1.1.1:58492;transport=TLS", <sip:user1@3.3.3.3:58520;transport=TLS;ob>;expires=244, <sip:user1@1.1.1.1:58529 ;transport=TLS;ob>;expires=284;received="sip:1.1.1.1:58529;transport=TLS", <sip:user1@3.3.3.3:58548;transport=TLS;ob>;expires=329, <sip:user1@3.3.3.3:58562;transport=TLS;ob>;expires=393, <sip:user1@1.1.1.1:58571 ;transport=TLS;ob>;expires=483;received="sip:1.1.1.1:58571;transport=TLS", <sip:user1@2.2.2.2:58588;transport=TLS;ob>;expires=538, <sip:user1@1.1.1.1:58600 ;transport=TLS;ob>;expires=587;received="sip:1.1.1.1:58600;transport=TLS", <sip:user1@2.2.2.2:58611;transport=TLS;ob>;expires=630, <sip:user1@1.1.1.1:58624 ;transport=TLS;ob>;expires=670;received="sip:1.1.1.1:58624;transport=TLS", <sip:user1@2.2.2.2:58632;transport=TLS;ob>;expires=706, <sip:user1@1.1.1.1:58650 ;transport=TLS;ob>;expires=826;received="sip:1.1.1.1:58650;transport=TLS", <sip:user1@2.2.2.2:58661 ;transport=TLS;ob>;expires=900;+sip.instance="<urn:uuid:00000000-0000-0000-0000-00007dtrf0a4c>";reg-id=1 Why is that ? -- Khoa Pham HCMC University of Science www.fantageek.com