UL and DL (HR)
I work with Huawei, but Its the same, in the past I work with Siemens, and the differences are minimum.
Try to deactivate DTX on HR, In my experience DTX affect HR Voice Quality, and we don’t care to save battery on phones, I rather keep voice quality.
And remember wen u use AMR, its recommending increase Radio Link Time Out to 64, we can save voice quality but the carrier quality its the same.