Sometimes you might like to modify the way that SIP messages are processed on Lync servers.  Microsoft SIP Processing Language (MSPL) allows you to do just that.  You can write a MSPL "message filter" to filter and route/reroute messages in Lync Server 2010 applications.

(HT: Ken Lasko for a really good example of using this feature to route calls that would fail without it)

What kinds of things can you do to a SIP message with MSPL?  A full list of MSPL built-in functions can be found here, but just some examples are:

:

AddHeader         – Adds a header to the current SIP message

Fork            – Creates a forked copy of the current message with its request URI field set to the supplied URI string.

Respond         – Generates a SIP response to the current request message with the supplied status code and reason phrase

Proxy Request/Response – Proxies the current SIP request or response.

 

Check out the  additional references below.

References:

MSPL Scripting Reference:     http://msdn.microsoft.com/en-us/library/gg425301.aspx