SIP over TCP has a significant advantage over UDP for mobile devices. The reason is due to the use of NAT, and how NAT table entries in a wireless router or a cell providers' router are generally timed out much quicker for UDP vs TCP.

RFC 4168 - The Stream Control Transmission Protocol (SCTP RFC 4168 SCTP as a Transport for SIP October 2005 3.1.Advantages over UDP All the advantages that SCTP has over UDP regarding SIP transport are also shared by TCP. Below, there is a list of the general advantages that a connection-oriented transport protocol such as TCP or SCTP has over a connection-less transport protocol such as UDP. 3cx softphone provisioning UDP TCP TLS | 3CX - Software Jan 18, 2018 networking - IPTABLES port forwarding to SIP UDP not IPTABLES port forwarding to SIP UDP not working. Ask Question # iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j DNAT --to 192.168.1.2:8080 # iptables -A FORWARD -p tcp -d 192.168.1.2 --dport 8080 -j ACCEPT ###HTTP Forwarding Rule### iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j DNAT --to 10.0.4.1:80 iptables -A

IPTABLES port forwarding to SIP UDP not working. Ask Question # iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j DNAT --to 192.168.1.2:8080 # iptables -A FORWARD -p tcp -d 192.168.1.2 --dport 8080 -j ACCEPT ###HTTP Forwarding Rule### iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j DNAT --to 10.0.4.1:80 iptables -A

Apr 17, 2020 Asterisk client behind NAT - UDP registration does not If I change the client and server config to use UDP (from transport=tcp to transport=udp,tcp or even simply transport=udp) the phone can no longer register and Asterisk sends SIP: SIP/2.0 401 Unauthorized to the client. From what I have read it is possible to use UDP behind a NAT with Asterisk, however experience seems to dictate otherwise. System Configuration Guide for Cisco Unified

Does VoIP Use TCP or UDP? - Best Virtual Phone Systems

SIP over TCP has a significant advantage over UDP for mobile devices. The reason is due to the use of NAT, and how NAT table entries in a wireless router or a cell providers' router are generally timed out much quicker for UDP vs TCP. Nguyen, TCP or IDP are transport protocols for sip messaging. It doesn't impact phone features. Generally sip over udp is preferable, because it's such a light protocol however if you are in an environment where your sip messages will be larger over the traditional 1500 bytes of traffic then it is better to use tcp to a avoid fragmentation of sip packets by udp