im running a cisco e4200 latest firmware and the sprint latest airvana femtocell.
not had any issues with data or sms use. i had another user over who has a new evo lte also and they had no issues connecting, making calls, etc.
could be any number of things here.
how do you cats have the router? is it in front or behind the airavna?
do you have the latest FW for your routers?
do you use AUTO on all of your router settings? if so, try sticking to one channel and if you have channel bonding on your routers, force it to 20 or 40mhz.
disable DFS on the 5ghz side and pick a band to use.
reboot reboot reboot .