Hi, I am trying to explain something to myself so I'd appreciate someone shed some light on this ... Suppose we have softswitch (SS) with media gateway (MG) and signalling gateway (SG). I.e call is coming from PSTN and ISUP IAM message is coming via signalling link to SG. Inside that ISUP message there is CIC (Circuit Identification Code) saying which channel will be used on specific E1 link for voice/media. If signalling gateway has M3UA implemented, ISUP message is extracted and sent to SS (MGC - Media Gateway Controller). Now MGC needs to control/activate that specific channel inside E1 links on media gateway. Af far as I can see only master/slave voip protocols like MGCP/H.248 can implement this, i.e. control specific channel on specific port (i.e. channel 21 on second E1). It couldn't be done via SIP ? Or it could ? My point is, if everything is goind sip way, why is MGCP/Megaco still heavily used for controlling media gateways (when interconnecting with SS7 networks).
thanks, jmiklo