Registering a VoIP phone number to Apple ID

I'm using an VoIP based phone on both my iPad mini and my iMac desktop. I DO NOT have a carrier based iPhone number. So how can I associate my assigned VoIP phone number with iMessage? I can get iMessages using my email Apple ID, but this is way too confusing for other iPhone users who "text" to phone numbers and let iMessage resolve the message path.

In my opinion, Apple needs to either: (1) allow for the verfication & use of non-iPhone numbers in their Apple ID database, or (2) change iOS on the device to allow for the entry of an "Apple ID" into the contact's information. This "Apple ID" entry could then be used for both iMessage, and FaceTime.