7100G gaps and length of tones?

[Danc]

I have programmed certain numbers to automatically pause and then dial a code for office voicemails, etc. Sometimes some of the tones arbitrarily sound for a longer period and sometimes there is a longer gap between some of the tones. There is nothing consistent about this.

Any ideas? I thought that it might have to do with areas of poorer service strength but seems not to be the case. No big deal but it bugs me.