IVR Problem

I am running A@H and have been tested again and again. The IVR seems to be working fine when I test it using land line phone as well as my mobile phone. However, many a time when people call me, the Digital receptionist will pick up the call but when the caller press the option, it does not pick up the option and will do nothing. This happens with a number of calls especially with mobile calls and some land line calls.

Can anyone advise me how do I fix this issue with A@H