[Asterisk-Users] Hardware Compatibility Question

[Peter Svensson]

On Fri, 1 Oct 2004, Wolf N. Paul wrote:

> We have an E1/PRI phone company connection, and need to support about
> 100 analog POTS extensions, while also implementing VoIP for calls to
> the US and the UK.
>
> We also have a second E1 for Internet connectivity, terminating in a
> Cisco router.
> 
> It seems to me that the best thing would be to get a single-port Digium
> E1 card for the phone company link, and either a 4-port E1 or 4-port T1
> card with corresponding 24-port channel banks for the analog extensions.

The TE405P and TE410P 4-port cards are E1/T1 selectable per span.

There are advantages in keeping a call within one 4-port E1 card. The 
timing is not carried between cards so a call coming in on one card and 
going out over another card may have slips. Also, calls between cards have 
to cross the pci bus whereas connections between spans on the same card 
stay on the card.

You would almost get by with 3 E1 spans ( =90 pots lines). Unfortunalty E1 
channel banks are a lot more expensive. 

Do you plan to use transcoding for the VoIP trunks to reduce the bandwidth 
used? Depending on how much internal traffic you expect between the 
extensions you may want to handle the extensions on one machine and the 
external connections + transcoding for VoIP on another machine.

Peter