Cisco WS C4224V 8FXS Software Guide - Page 50

Recommended Configurations Chapter 1 Product Overview Trunking The Catalyst 4224 supports only dot1Q trunking. Dynamic Trunking Protocol (DTP) is not supported. A Catalyst switch that is trunked to the Catalyst 4224 must have the trunking mode set to either On or No negotiate and type dot1q. Fractional PRI Configuration The maximum of 16 channels are available for trunk voice ports. This can cause a problem when a PSTN or PBX uses an unavailable channel to send a call to the Catalyst 4224. To prevent this type of problem, follow this procedure: Step 1 Step 2 Always configure the Primary Rate Interface (PRI) VIC last (after you configure all the VIC cards that require the DSP resources). Allocate all 24 time slots for the PRI group. The following sample configuration shows a configuration for the range command. controller T1 1/0 framing esf linecode b8zs pri-group timeslots 1-24 Note The DSP resources are not sufficient for the 24 time slots. Therefore you receive this message: insufficient DSP resources. Ignore this message. Note You need to tell the switch or PBX to make the time slots out-of-service. If you do not allocate 24 time slots, a SERVICE message is not sent for the unallocated time slots. This is an important caveat. Step 3 Use the show voice dsp command to see how many channels are allocated with the available DSP resources. In a test case, 16 time slots could be allocated DSP resources. 1-24 Catalyst 4224 Access Gateway Switch Software Configuration Guide OL-2031-02