Durafon 1x hunt group issues

[phonesaz]

I have 3 durafon 1x units and 3 bases installed on an IPO R11. The incoming call route is a hunt group that rings all phones (they have about 10 digital handsets in addition to the Durafon handsets.) There are days when everything works perfectly, and days when the Durafon handsets won't answer incoming calls. There are less frequent issues with the phones not connecting on outbound calls, and occasionally the phones have some static. Each phone can also be called directly, and those calls never fail. The issue seems to be calls terminating to the hunt group. I am wondering if the bases are somehow interfering with each other. Engenius isn't much help. I have changed the bases to be 10, 20, and 30 instead of all defaulting to 10, have verified the RSSI settings on all of them, and am looking for any creative ideas. I am also wondering if shielded cable would make a difference - especially with the static. I've worked with a pretty smart engineer from this group and he is puzzled as well so I thought I'd just throw this to the group and see if anyone has any suggestions. Thank you in advance.