Resolution
The NM-HD-2V, NM-HD-2VE and NM-HDV2 voice network modules have enhanced Time-Division Multiplexing (TDM) capabilities. This allows synchronous digital audio or data bit streams to be switched between different ports on the same network module.
It does not need any Digital Signal Processor (DSP) resources to remain in the media path. As a result, ISDN calls that use a data or voice bearer capability are locally switched between interfaces on the network module. The feature allows PRI to PRI, PRI to BRI, BRI to PRI or BRI to BRI call switching if these interfaces are installed on the network module.
The ISDN D-channel for each interface is processed locally inside Cisco IOS Software. It is based on the called numbers (Dialed Number Identification Service [DNIS]) contained in the ISDN Q.931 setup message. The call is matched and routed using other Plain Old Telephone Service (POTS) dial peers.
This feature allows the NM-HD-2V, NM-HD-2VE and NM-HDV2 voice cards to switch voice and data calls between BRI and PRI ports. Possible applications for this technique include ISDN BRI Dial-On-Demand Routing (DDR) testing, connection of BRI based video conferencing units to PRI services, integration of BRI based PBXs to PRI services and BRI to PRI data call switching.
Note: Digital interfaces that use the TDM switching feature must be on the same network module. It is not possible to switch non-voice traffic across a router backplane to a different network module. Also, the NM-HD-2V card only supports BRI to BRI TDM switching because the card does not support channelized E1 or T1 interfaces. Channelized E1 or T1 interfaces only work with the NM-HD-2VE or NM-HDV2 network modules. Cisco IOS Software does not support all features provided by some ISDN service providers.
For more information on the TDM switching feature, refer to ISDN Voice, Video and Data Call Switching with Router TDM Switching Features .
