The problem could be related to buggy SIP ALG implementation in the router. I suggest to temporary connect ATA directly to the modem, bypass the router. Will the problem persist?--»www.callwithus.com
Router is Netgear WNDR4000. What settings should I check?
Try to bypass router before making any changes in settings. See »wiki.freeswitch.org/wiki/ALG and »www.voip-info.org/wiki/view/Routers+SIP+ALG for more details.--»www.callwithus.com