To save yourself allot of money and headache, you may want to look at the new VoIP (Voice Over IP) options. It will not only save you money on the equipment, but the compression rates for an IP call versus a standard voice call saves you about 5x’s the bandwidth for your IPLC requirements. The quality is almost identical to that of a traditional voice call.
I have implemented these solutions and would be happy to discuss this with you.
Tim Harvey