One interesting aspect of Media Processing in the telco space is how the application server controls the Media Server or Media Gateway.  In the traditional telco setup, media gateways have for a long time used protocols like H.248/Megaco and MGCP to make a tight controlling relationship between a Media Gateway Controller and the Media Gateway itself.  In GSM (IN) networks there’s a specialised component for media processing called the gsmSRF (Special Resource Function) that takes care of announcements and digit collection.  In this case the gateway control is done using the SS7 protocols CAMEL.  Of course the World these days is all about the web, and we’ve seen a rapid development in Media Servers that process only RTP streams, and at the control interface use SIP-based control languages, like MSML (Media Sessions Markup Language).  

There are a lot of  interesting transitions going on right now, with traditional media gateways getting MSML interfaces in addition to H.248, and media gateways being replaced or augmented with media servers, which don’t have TDM interfaces.  Also, traditional IN networks are in transition to IMS (IP Multimedia Subsystem), which means that SS7 and SIP control systems have to run side-by-side and even interwork.  One result of this is a ‘magic’ box called the IM-SSF (Service Switching Function) which makes the CAMEL network  talk SIP, and likewise makes a SIP application server look like a CAMEL application server.  There’s also a kind of weird situation in IMS where today only H.248 is specified as a control language for the MRFP (Media Resource Function Processor, the media server for IMS).  Many say that this doesn’t make much sense, since SIP is used for all the signalling control in IMS, so surely the MRFP should talk SIP to its application servers too?  It’s likely that MSML will eventually be part of the IMS standards to make this come true. 

Looking around in Dialogic I can see that we are in a very different situation than six months ago, and the breadth of the product line means that often we have more than one solution to offer for each problem.  So it is with media processing, where our different divisions have served different markets in the past, such as the ‘web guys’ and the ‘telco guys’.  Now that these worlds are colliding, we have our work cut out to make sure the different product lines also converge and cooperate to allow the flexibility the customers need.