silent calls

[wciagatune]

what are the main causes of silent calls in 2G network & what are the solutions.

[omar mohsen]

One reason for silent calls that you have a downlink signal but you cant send in the uplink signal, this can appear in in-door coverage specially when using directional antenna and you are in the back loop of this antenna

[Chinaman]

Silent calls are mostly caused by problems with timeslot mapping on the Abis interface. Signalling and voice traffic are transported to the BSC on different timeslots, hence if the voice timeslot is not working, then you have a silent call that doesn't drop because the signalling is still being received by the BSC.
I had a strange experience with this before, where a perfectly good call would hand-in to a cells with Abis problems and immediately we would have a silent call or enormous echo.
When the call hand-over to another cell, all would be perfect again. In this case it was caused by an E1 terminated with a loop plug rather then being connected to the BSC.....