Hello, I have installed T1 card and Adtran TSU 600. Everything works ok but... When I am making local (in our local network) calls using FXS ports with Adtran ,connected with asterisk using T1 card, to a SIP phone also in our local network everything works very good. Problems start when I am making calls using Adtran outside our local network (for example internet) to SIP destination. The voice is getting choppy... But when I am making call using SIP phone to the same destination call is OK. What could be the problem ? Regards, bartosz