Hi Sudhir
here a description how the system assign the channel.
Before assigning a channel (i.e. for Assignment or HO procedure) the BSC determines the percentage of TCHs not available for TCH allocation. This is done by
dividing the total number of TCHs not available for calls (i.e. locked, failed or busy) divided by the total number of configured TCHs within the cell (TCH\F corresponds
to 2 channel and TCH\H to 1).
When the percentage of TCHs not available for TCH allocation has been determined two cases are possible:
a) If the calculated percentage is equal or below the threshold entered by TINT the BSC assigns a full rate TCH no matter which speech version the requesting MS
indicates as ‘preferred’ .
b) If the calculated percentage is above the threshold entered by TINT the BSC assigns half rate TCH for all mobiles which indicate half rate version 1 as supported
speech version, no matter which speech version the requesting MS indicates as ‘preferred’