Inbound Calls Garbled Sound

I am having an issue that seems somewhat odd.

Whenever people are calling in, the receptionist is telling me that she can not understand what they are saying. They understand her fine, and when she places an outgoing call she can hear people just fine. But, with incoming calls, its no dice?

What could possibly be the cause of this issue. (I am using the same provider for incoming and outgoing calls?)

This is on a fiber 10/10 line, and this office has 10 employee’s. (no bandwidth issues… as well as QoS in place).