I have a Trixbox system with a Digium TDM800 FXO and SIP trunks by multiple providers. System is a Dell 2650 running Centos and Trixbox CE. The problem is when I dial any number through the SIP trunks to say Verizon for example and try to navigate the menu's I can dial the different menu items but can not enter numbers. Like if I try to enter my account number the number is so scrambled I get kicked off. Other numbers I dial that repeat the numbers back to verify what i have entered will many times repeat them in two's and threes. If I dial out on the POTS lines everything works perfect. I have the system configured with the phones (Polycoms) on the LAN and the VoIP on the WAN. Equipment out from there is an Cisco ASA 5510 firewall and a Cisco 2821 router. I have UDP and TCP 5060 for SIP open and RTP 1024 - 64000 UDP. The problem occurs on all SIP trunks regardless of provider. Audio quality is good otherwise. I have been working with support on this but have not gotten anywhere as of yet. Any insight would be greatly appreciated. I have 3 Trunk providers Bandwidth, Voicepulse, and Link2VoIP and this problem occurs on all of them.