Here are few things we have done to investigate this issue,
DTX was disabled for AMR FR and HR and Interference HOs restored to their orignal value and as soon as it was enabled again INTF HOs increased.
According to ALU this degrdation is simply due to inaccurate measurement reporting by MS because of DTX and nothing else.
ALU is using VAD2 for DTX with AMR.
Vendor is suggesting to use W_QUAL_HO parameter to give more weightage to non DTX measurements in averaging process so that averages are less impacted by inaccurate DTX measurements.
What do you say???????