The number that some voip providers give to the 911 center is not your number at all but is a number that if the 911 center dials the number it will ring your phone.
This is a very important point, and has been discussed on the forum over the years. The address is presented, and the callback number is a TEMPORARY number (from many services) that works for a period of time so that the 911 operator can call you back. This "invisible DID" is visible to 911, and they may tell it to you if you ask, but isn't going to work for someone to call you a few days later and should not be used in that manner.
One benefit of this is that if you forward your number at the provider to another number, but someone in your home calls 911, the device at your home will ring when 911 calls back as it ignores call treatment like forwarding.