46 - is for RTP (voice payload). The default for signalling (that includes MGCP) is 26 (AF31). That can be changed under dial-pear . Yo can also check the current DCSP setting for both payload and signalling by "show dial-pear voice "The fact that DS...
those two features are independend. dialer-list defines what traffic triggers the call and reset idle timer. load-threshold defines under what link utilization the second (and subsequent) B-channels are activated (does not matter if the traffic is in...
The packets are send to the FR provider's network with the speed of the physical main interface (trunk as you call it). So if that access port speed is T1 or higher, the serialization delay caused by 1500 packet will be less that 10 msec, so there sh...