4760i e1 trunk voice call drop from outside after 1 beep

[swat291]

Good day to every one. Im newbie here.

We provided e1 trunk on PRA t2 plate on 4760i.

If i try call to number from outside to external number which leads to internal number and if call not accepted after 1 beep
then call drops

if i catch call with in 1 beep everything is ok and call can be proceed.

which setting in MGR can fix this issue ?

MGR > System > Timers ???

[vad]

make t3 trace and show us.
And - PRA T2 in OXE PBX. 4760i - just management program.