pvdm?

itdaddy

do I need a pvdm for fxo and fxs cards?

Okay I am goingto buy 2 x fxs cards for my cisco 1760 routers to hook up
2 pots phones
and I am buying 1 x fxo card

so then I would need 3 x pvdms????

thanks

hypnotoad

itdaddy wrote: »

do I need a pvdm for fxo and fxs cards?
Okay I am goingto buy 2 x fxs cards for my cisco 1760 routers to hook up
2 pots phones
and I am buying 1 x fxo card
so then I would need 3 x pvdms????
thanks

No, you need basically one or two PVDM's capable of running 3+ channels. The 1760 has two slots I believe.

Cisco 1751 and Cisco 1760 routers use the following PVDMs (http://www.cisco.com/en/US/docs/routers/access/1700/1751/software/feature/guide/dsp_cn.html):
•PVDM-256K-4 (1 DSP)
•PVDM-256K-8 (2 DSPs)
•PVDM-256K-12 (3 DSPs)
•PVDM-256K-16HD (4 DSPs)
•PVDM-256K-20HD (5 DSPs)

The number on the end is the number of channels it will run. So a -4 would run 4 channels. You might ask, when would I need 12 or more channels in my 1760? Well, while analog wic cards are just a couple channels, a T1 is ~24 channels.

Also, one DSP can serve 4 analog voice ports. So you have to take number of DSPs in to account as well as number of channels.

Hope this helps,
HT

By the way, this is all assuming you run plain old G.711 codec, if you have to convert between codecs ("transcoding"), it will use more resources, but that can be easily calculated and accounted for. Google "cisco dsp calculator".