The ASUs hook up to the embedded cim ports. As for needing the ASUs to get to 120 extensions, you got me there. The MX controller supports 248 IP Phones. To program the ASUs make sure that the cims aren't assigned to bays in form 53, and assign them in form 1 to slots 14 & 15 of the ip bay.

Oh now I see you are talking about a total 0f 120 analog. How is your per node setup?