An enterprise license correct me if I am wrong if for a multiple controller deployment site. As far as licensing on the multitech you would buy a unit and then you would need a DSP II and T38 licenses and SIP Trunk Licenses for the Site.
IE
Remote 1 - 1 Fax and 1 Phone
Remote 2 - 1 Fax and 1 Phone
2 Multitechs, 1 DSP II, 2 T38 Licenses, 2 SIP Trunks
Of course that is bare bones and could be configured differently. While a local trunk would be cheaper up front a deployment like this would save over the long haul.