When T1s are ordered, some carriers make the trunk group portion more obvious than others. Having never order a voice T1 from XO, I don't know how obvious, or how much help their provisioning department provides.
When I ordered a T1 from Airespring for my company, I saw on the order form, spaces to specify trunk grouping. After discussing this with one of their techs, my boss, and my phone vendor, ESI, I figured out how it would be useful.
We have 5 groups of channels.
Lines 1 - 6 handle incoming calls for a group of 9 800 numbers. All incoming calls are hunted from the first line-up. In other words, the first call to any of these numbers goes to line 1. When the second call comes in, if line 1 is busy, it will hit line 2, and so on.
Lines 7 - 10 handle only 1 800 number, and we'll probably drop it soon.
Lines 11 - 16 have another group of 10 800 numbers, and behave similarly. These lines are dedicated for a secondary company we share the office with.
Lines 17 - 20 is for yet a third company, with 1 800 number.
21 - 24 are what we've dubbed an overflow group. When any other group's channels are completely busy, any calls to them hunt into this group. This group also has some 800 numbers we haven't assigned a purpose yet.
What it seems like has happened, is that none of this trunk grouping was defined on the initital order. While XO may not be the one responsible for performing the hunt, some carrier down the line IS. In my case, I contracted with Airespring, who is actually reselling Broadwing service, which is delivered on Verizon wires. It was with Broadwing who I had to detail my hunting scheme with, as the Airespring guy was getting too confused.
No single-T1 channel bank that I'm aware of will handle the hunting for you. Some carrier is responsible for it, and what you need to do is arrange the trunk groups. In your case it sounds like you want 24 trunk groups each with 1 line each. Each group is associated with only 1 phone number. However, in this arrangement, only one call can be handled by a particular phone number at one time - subsequent callers will get a busy tone.
On a side-note, I happen to work for a company that does call-center software, including the IVR part... and the application you're trying to build is precisely what we're good at. The others have all said that there's equipment designed specifically for this, and they're right. But I think it's easier to wrap my head around a software approach....
