New user System requirements


#1

This post is going to be like so many other posts but I hope you all will bear with me. We are looking at replacing our creaky old phone system with Asterisk and I have a few questions.
Right now we are planning on using a TDM2400P to interface with our current POTS lines. We have 22 out going POTS lines. We will have 50 extensions and we are planning on starting off with soft-phones for now.
For the server we will build an Athlon-64 box with a gigabyte of ECC ram, a SATA RAID, redundant hot swappable power supplies, and 1000Base-T. We will probably use a 4u case.
We will upgrade the network from 100BaseT hubs to 100Base-T switches that support QoS/CoC with a 1000Base-T backbone. The Asterisk server will be located on the back bone as will our other servers.
Once we get ride of the old phone system we can convert the current internal phone lines to switched 100Base-T PoE ports and then migrate to VoIP hard phones.

Here are my questions. One of the people here is convinced that we have to go to 1000Base-T with PoE before we move to Asterisk. I don’t see any advantage to 1000Base-T for the phones. Is a 100Base-T switched network good enough for our needs? We don’t stream any video in house or copy massive files around so I question the value of 1000Base-T even for data.
Will the server I specified work well for our size of office? We are a support call center and are averaging around 600 calls a day. It is very likely that we will have 15 or more calls going on at the same time.
Any input will be great. thank you.