The TA850 with 16Fxs bundle is a sturdy, light duty router and voice demux that offers consistent service. It is easy to troubleshoot, and has shown few problems with the exception of the firmware. Various versions from Adtran have exhibited problems, call dropping and ip routing being two that I am most familiar with. Adtran has been good about fixing the problems when they are identified.Documentation for the unit is expansive but leaves a lot to be desired regarding specific functions, how to program them in, etc.
Diagnostics for network and module performance are excellent.
