Cannot transfer call to voicemail

I have a setup where a receptionist will transfer calls to people’s voicemail if they aren’t available. This works fine with the exception of one extension. The caller will get a message stating that their own DID is unavailable, “goodbye”. For example, if I was calling them and my number was 555-555-5555, when the receptionist transfers me to this particular extension, I will hear a message stating that “555-555-5555 is unavailable, goodbye”.

Does anyone have any idea why this is happening?

I only ask because i can not seem to get it to work at all.

what is the correct button sequence to make this happen?

oh… im pretty new to free PBX and Voip Hosting.