DSP Card Resources
The maximum number of simultaneous calls using IP protocols is determined by the type of call, codec(s) used,
and digital signal processor (DSP) card installed in the PBX.
Below are some example configurations and the maximum number of simultaneous calls for each.
For Calls between Virtual CO Lines and Virtual Extensions
Codec(s) Used
Maximum Number of Simultaneous Calls
DSP4 Card DSP16 Card DSP64 Card
G.711 8 32 64
G.711+G.729A*1 2 12 42
G.729A 2 8 32
*1 For example, when a virtual extension uses G.711 and a virtual CO line uses G.729A for the same call.
For Calls between Virtual CO Lines and Physical Card Extensions (e.g., DPTs, etc.)
Codec Used
Maximum Number of Simultaneous Calls
DSP4 Card DSP16 Card DSP64 Card
G.711 5 32 64
G.729A 2 12 50
For Calls between Virtual Extensions and Physical Card Extensions/CO Lines (e.g., PRI, etc.)
Codec Used
Maximum Number of Simultaneous Calls
DSP4 Card DSP16 Card DSP64 Card
G.711 16 64 113
G.729A 4 16 64
Note
For non-peer-to-peer calls via the DSP card, calls cannot be made or received when all of the card's
resources are being used.
32 Installation Manual Document Version 2011-10
1.3.3 System Capacity