Grandstream phones missing numbers when dialing auto atten

I have 1 setup with grandstream gxp2000’s where they are having issues when calling a number where they have to type in a bunch of numbers. I have verified this issue. If you dial slow enough it works 100% of the time . If you dial too quickly it seems to miss numbers. I have tried turning quick dial on and off. I have also tried changing dtmf modes. I still have the same issue. Anyone got any ideas?