12 Apr

Passing username in CUBE-SP

By default when register message passes SBC username in contact field is replaced with random string. This string identifies pinhole opened for particular user for management purposes. But this behavior is not always desirable. Many SIP implementations identifies user by Contact field and rewriting it with random string would prevent application from registration.
SBC can be configured to pass username set in Contact field. To do this you have to configure

    registration contact username passthrough

This have to be set on adjacency that should not rewrite username when SIP REGISTER comes from

13 Mar

Passing SIP methods in CUBE-SP

CUBE is marketing name of Cisco Unified Border Element, formerly known as Session Border Control. It’s meant to be implemented at the edge of the voice network as an interconnection between two or more VoIP networks providing security between them, CAC, billing etc. There are two models – CUBE known from IRS routers and CUBE-SP available on ASR 1000 and 7600 platform. Both of them works slightly different.

With CUBE-SP not all of the SIP methods are passed through SBC router by default. In example MESSAGE method is not which makes sending text messages between SIP phones impossible. SBC router responds with “405 Method now allowed” if it sees unsupported method in SIP message. But particular methods can be added to whitelist and therefor passed through SBC.

sbc CUBE
   sip method-profile Pass-IM-Header
    method MESSAGE
     action pass
   adjacency sip Internal
    method-profile inbound Pass-IM-Header
    method-profile outbound Pass-IM-Header
   adjacency sip Internet
    method-profile inbound Pass-IM-Header
    method-profile outbound Pass-IM-Header

In following example particular method is defined as accepted in method-profile, which is attached in both ways to adjacency. This way we can biuld complex policies allowing devices from one adjacency to pass some methods while blocking from others.