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Core Issue

Cisco 2800 Series Integrated Services Routers support the same five Packet Voice/Data Modules (PVDMs) that are supported on the IP Communications High-Density Digital Voice Network Module (NM-HDV2). The supported PVDMs are:

  • PVDM2-8
  • PVDM2-16
  • PVDM2-32
  • PVDM2-48
  • PVDM2-64

Note: The number in the suffix (for example, the 8 in PVDM2-8) is a measure of the PVDM voice-processing capacity and indicates the number of G.711 channels that the PVDM supports.

Cisco 2821 and 2851 Series routers have three PVDM slots. Based on the number of Digital Signal Processors (DSPs) available on the router, different voice cards and modules can be configured on the router.


To resolve this issue, calculate the number of DSPs consumed by the current configuration (T1, Foreign Exchange Office (FXO), Foreign Exchange Service (FXS)) on the Cisco 2800 Series router with the DSP Calculator. A fully loaded T1 consumes 24 channels. One channel each is consumed for FXO and FXS configurations. Determine the number of DSPs free to be configured for a new T1 connection.

If the existing configuration consumes the available DSPs, either delete the unused existing configuration or purchase more DSPs for the 2800 Series router (from the list of supported PVDMs).

For more information, refer to Cisco 2800 Series Integrated Services Routers.

The number of DSPs consumed by a Cisco 3825 Series Integrated Services Router with two T1 PRIs and eight FXO/FXS ports, if it has a PVDM2-64.

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