Please see this link:
http://www.cisco.com/univercd/cc/td/doc/product/voice/ics7750/swconfig/c_trunk.htm
Here is what is supported:
Configurations Supported on a Single MRP
The MRP supports the following T1/E1 port configurations:
Maximum of two T1/E1 ports with voice payload. Even though the MRP can configure two T1/E1 voice ports, it can only make 24 simultaneous calls (T1)/30 simultaneous calls (E1).
Maximum of one T1/E1 data port.
Only one channelized T1/E1 group for data.
Maximum of two external clock sources.
If the MRP has one PVDM, only one clock source is available.
If the MRP has an analog VIC, only one external clock source is available for T1/E1 ports.
If there is only one clock source, DSPs on both PVDMs are shared.
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Note The DSPs on analog PVDMs are not shared with the DSPs on digital PVDMs.
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Each DSP handles up to eight digital signaling channels and up to four analog signaling channels (using the medium complexity image on an ASI). For more information on DSP calls, see "Codec/DSP Overview".
T1 CAS and ISDN PRI (on separate VWIC ports).
T1/E1 channel-groups and PRI voice (on separate VWIC ports).
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Note Define the port exporting the clock before you import a clock source from it.
