Thanks for your answers.
1st Ho means that after call setup and TCH assignment if handover happens (Dual band configuration: Call is set up in GSM and then handovered to DCS band) problem that I described eralier happens.
But problem occurs even if there is no DCS:
Call is set up in one 900Mhz Cell, Alerting starts, MS moves and then is HO to another 900Mhz cell, UL quality jumps to 7 and stays, BSC trays to Ho it to another, then another then another cell, then comes Connect message, conversation starts and problem disapears.
If there is no handver (MS stays in the same cell all the time till Connect message) problem doesnt occure.
Sub and Full measurements both report UL Quality 7
Problem occurs only in cells where AMR is enabled and if for particular call AMR is not used, even if AMR is enabled, then problem doesnt occur.
TFO is disabled.