Hello. kamailio -v version: kamailio 5.4.8 (x86_64/linux) flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown compiled with gcc 8.3.0 How can I disable GRUU support completely? Sip client Grandstream NT-XXX sends default registration request with "reg-id" and "instance" REGISTER sip:kamailio3.telecom.ru SIP/2.0 Via: SIP/2.0/UDP 172.17.0.252:5060;branch=z9hG4bK1645839794;rport From: "7777" sip:7777@kamailio3.telecom.ru;tag=53756161 To: sip:7777@kamailio3.telecom.ru Call-ID: 308071885-5060-1 CSeq: 2031 REGISTER Contact: sip:7777@172.17.0.252:5060 ;reg-id=1;+sip.instance="urn:uuid:00000000-0000-1000-8000-000B82566BBB" Authorization: Digest username="7777", realm="kamailio3.telecom.ru", nonce="Ysv842LL+7dABGNcyuYZhl1L2QTPgzFq", uri="sip:kamailio3.telecom.ru", response="0ef43a754a7422dd9d8ed36f91aa546 , algorithm=MD5 Max-Forwards: 70 User-Agent: Grandstream HT-502 V2.0A 1.0.9.1 chip V2.2 Supported: path Expires: 1800 Allow: INVITE, ACK, OPTIONS, CANCEL, BYE, SUBSCRIBE, NOTIFY, INFO, REFER, UPDATE Content-Length: 0 SIP/2.0 200 OK Via: SIP/2.0/UDP 172.17.0.252:5060 ;branch=z9hG4bK1645839794;rport=5060;received=172.17.0.252 From: "7777" sip:7777@kamailio3.telecom.ru;tag=53756161 To: sip:7777@kamailio3.telecom.ru ;tag=5bf75eb19869d3e257cd1fde2cbf92c4.7224507f Call-ID: 308071885-5060-1 CSeq: 2031 REGISTER Contact: sip:7777@172.17.0.252:5060;expires=1800;+sip.instance="urn:uuid:00000000-0000-1000-8000-000B82566BBB";reg-id=1, sip:07777@172.17.0.250:5060;expires=101, <sip:7777@172.1 0.250:5061>;expires=101, sip:7777@172.17.0.252:5062 ;expires=607;+sip.instance="urn:uuid:00000000-0000-1000-8000-000B82566BBB";reg-id=2 Server: kamailio (5.4.8 (x86_64/linux)) Content-Length: 0 REGISTER sip:kamailio3.telecom.ru SIP/2.0 Via: SIP/2.0/UDP 172.17.0.252:5062;branch=z9hG4bK212965390;rport From: "7777" sip:7777@kamailio3.telecom.ru;tag=1540711120 To: sip:7777@kamailio3.telecom.ru Call-ID: 1127299103-5062-1 CSeq: 2031 REGISTER Contact: sip:7777@172.17.0.252:5062 ;reg-id=2;+sip.instance="urn:uuid:00000000-0000-1000-8000-000B82566BBB" Authorization: Digest username="7777", realm="kamailio3.telecom.ru", nonce="Ysv862LL+78cGZE/vXJnQfemhCMiBilm", uri="sip:kamailio3.telecom.ru", response="6c3333159d41ae0fcaabfbbd8c5026e , algorithm=MD5 Max-Forwards: 70 User-Agent: Grandstream HT-502 V2.0A 1.0.9.1 chip V2.2 Supported: path Expires: 1800 Allow: INVITE, ACK, OPTIONS, CANCEL, BYE, SUBSCRIBE, NOTIFY, INFO, REFER, UPDATE Content-Length: 0 SIP/2.0 200 OK Via: SIP/2.0/UDP 172.17.0.252:5062 ;branch=z9hG4bK212965390;rport=5062;received=172.17.0.252 From: "7777" sip:7777@kamailio3.telecom.ru;tag=1540711120 To: sip:7777@kamailio3.telecom.ru ;tag=5bf75eb19869d3e257cd1fde2cbf92c4.451b5a53 Call-ID: 1127299103-5062-1 CSeq: 2031 REGISTER Contact: sip:7777@172.17.0.252:5060;expires=1792;+sip.instance="urn:uuid:00000000-0000-1000-8000-000B82566BBB";reg-id=1, sip:7777@172.17.0.250:5060;expires=93, <sip:7777@172.17 .250:5061>;expires=93, sip:7777@172.17.0.252:5062 ;expires=1800;+sip.instance="urn:uuid:00000000-0000-1000-8000-000B82566BBB";reg-id=2 Server: kamailio (5.4.8 (x86_64/linux)) Content-Length: 0 Later, when I use branching (with q=-1.0), the kamailio sends an Invite to only one Contact from 7777@172.17.0.252:5062 If I use another Sip client without "instance" , such as Linksys-PAP2T, branching works fine. GRUU is always disabled modparam("registrar", "gruu_enabled", 0)