Head scratcher....

Customer purchased a prepackaged SL2100 online. I got the call to install the unit. They have 5 CO lines from Spectrum/Charter. During install, did the CO line calibration. All has been working well over the past 6 months. All of the sudden they are experiencing random dropped calls across all of the lines. No perfect pattern yet, but seems to happen on incoming calls more than outgoing calls. Lines test fine from Spectrums end. Reset the Spectrum MTAs (pull power and battery for 5 minutes). Restarted the SL2100. Did another CO line calibration and seemed to help the next morning, but the issue came back that afternoon....

Any other thoughts? Hardware issue ...on multiple CO cards?? Ordering replacement CO cards but kinda at a loss...

JB