it’s from theory… in reality
1. your BSS is carrying more subscribers –> more load, more signalling –> more risk of failures
2. the HR codec is a little less protected than the enhanced full rate, so it’s *slightly* more sensitive to interferences. But it’s noticeable only if the frequency planning is bad in many areas.
to fight problem 1 –> contact your vendor so they can fix their machines
to fight problem 2 –> activate AMR HR, which provides more resistant codecs than the legacy HR.