[Asterisk-Users] Hardware for PBX with 4 incoming/outgoing lines and 20 phones

[Andrew Elchuk]

Hi

I am interested in setting up an Asterisk PBX in my office with digium 
hardware, and I just have a few questions in regards to what I would 
need.  It is my understanding that an FXO card is used to interface with 
an incoming/outgoing phone line, and an FXS card is used for interfacing 
with a phone within the system.  Currently we have 4 incoming/outgoing 
phone lines and would like to have 20 phones in the system.  In order to 
accomodate this, would you either reccommend having 1 TDM04B (4 FXO 
modules on it) for the 4 incoming/outgoing lines, and 5 TDM40B (4 FXS 
modules on each) for the 20 phones we would have in the system.  Or 
would you reccommend 1 TDM04B for the 4 incoming/outgoing lines, and a 
T100P connected to a channel bank of some sort to connect to the 
internal phones?  If you reccommend the T100P and channel bank, where do 
you suggest I get an FXS channel bank?  Please let me know if I got any 
of this mixed up (like if I got the FXO and FXS cards mixed up) and 
thank you in advance for your help in us deciding the hardware we need 
for a new PBX.

Andrew Elchuk

P.S.  We are currently using an X-Like software phone with a free world 
dialup account for communication with our other office in a different 
city.  My question is if I can configure the extensions.conf to connect 
to a free world dialup number when executing a dial command, or would I 
need to edit sip.conf as well or some other configs or is that even 
possible?  Thank you again.

-- 
Andrew Elchuk
Technical Associate
Cronus Technologies
248 - 111 Research Drive
Saskatoon, SK  S7N 2X8
Tel: (306) 652-5798 ext. 112
Fax: (306) 652-5799
Toll Free: 1-877-655-5798
http://www.cronustech.com