If Proxy and/or Registrar, Inbound proxy and/or Outbound proxy are configured via the WBM, each incoming call is checked if the partner address is configured. If not, the call is rejected (with 403 Forbidden).

Hint: when not using profiles for native SIP Trunk there is no checking against the partner IP making the gateway vulnerable to SIP calls being spoofed. It must be then ensured the gateway is protected in other ways e.g. using VLAN separation from client network etc.

Trunk profiles are already tailored to the specific needs of a SIP trunk partner, e.g. if in an outgoing FROM header account or call number should be sent.

Generic Profiles are available where a partner is not certified.

DNS SRV propagates via DNS which IP-based services (e.g. SIP) in a domain (e.g. SIP provider domain) are provided. More than one partner IP address can be configured using DNS/ SRV

DNS SRV timeout is influenced by two factors:

Transaction timeout configured in:

Blocking timeout

For example, if DNS SRV contains two partners IP addresses, IP1 and IP2, when there is no answer at an Invite to IP1, for UDP only the GW retransmits the request, until timeout. First after 500ms, then doubles the interval after each retransmission. Then, after transaction timeout, IP2 is contacted, for current and next transactions, for the period of "blocking timeout" and IP1 is banned.

Notes: