What kind of trunks do they have - copper or coax/cable company? I've had coax company modems get flakey, and i've seen where a customer was located close to a TV/am/fm radio transmitter tower have issues because of the localized high levels of RF on the system/cabling feeding the system.
What version of s/w is in the system now? Also check before you upgrade, what version of s/w is on the UNI card, if its a V4 (instead of V5) you might have troubles with that also during the upgrade.
