This billing is a nightmare.
I bought the billing for a T1 system, but the billing crash every time that there is high volume of calls.
The support is a disaster, with people that barely speak english, and they want to do everything via MSM.
They will keep you on IM for hours, only to find out that the guy that was handling your trouble is gone for the day.
Save yourself the headache. But something that have a real support group.