SIP setting: outboundproxy

New in Asterisk 1.2

 outboundproxy = IP_address or DNS SRV name

SRV name, hostname, or IP address of the outbound SIP Proxy (DNS SRV excluding the _sip._udp prefix)

Use cases

Typical proxies are OpenSER, SER. Another product is sipproxd which can act as a transparent proxy for Asterisk, i.e. you do not need to activate the outboundproxy= setting in sip.conf.

• you might want to protect Asterisk boxes and place them inside your LAN whereas the SIP proxy is in your DMZ or exposed to the Internet
• you might want to add support for either SIP-over-TCP (for Microsoft Speech products) or TLS/SRTP for encryption
• you might want to load balance several Asterisk boxes

Example

 outboundproxy=proxy.provider.domain    ; send outbound signaling to this proxy, not directly to the peer
                                        ; Call-limits will not be enforced on real-time peers,
                                        ; since they are not stored in-memory

Notes

Be aware: Asterisk 1.2 is known to have incomplete/partially buggy outboundproxy support. Asterisk 1.6 (currently under development) will probably come with support for two types of outboundproxy settings, one where only the first message of a SIP dialog is sent to the proxy and we rely on Via: headers for all subsequent messages, and secondly the current implementation where Asterisk blindly sends everything through the the proxy.

See also

• Asterisk sip outboundproxyport or simply Asterisk sip port
• Asterisk config sip.conf
• Asterisk at large