Check your dimensioning of traffic for the cell/site, existing cell/site using static TCHs or dynamic TCHs settings?
AMR uses smooth transition between different bit rates and TCH HR-FR modes by determining the C/I condition, and also determining the congestion. The feature is also an anti-inteference tech, so you’d be allow to use more HR under bad air interface conditions. So it actually “increases” your capacity. (Only from Huawei equipment point of view, not sure other vendors using these paramters in AMR feature)