Problems with Call Forwarding

I was under the impression that when I set up Call Forwarding, all calls to my phone number will be sent to the phone number that I set up to receive calls -- but that the phone message that comes on if the forwarded number/phone is not answered should still be the message that comes on at my phone. Is this true? If so, can someone tell me what technical difficulties our phone (or phones) are experiencing and what to do?

I forwarded all calls from our home number (Wide Open West Phone/Internet/Cable. The phone is a cordless Vtech) to my sister's cell phone (Tracfone/Motorola/Safelink Service), since we were going to be gone for a while. I pressed *72 and my sister's number. She answered, which confirmed that everything was set up correctly.

While we were out, we received one call that we answered. When I got home, I deactivated Call Forwarding by pressing *73.

Everything was quiet for the evening. However, today, I was told by two people that they tried to call my home phone number after I deactivated Call Forwarding, but got my sister's cell phone's voice mail message. They just hung up.

Even if I had forgotten to deactivate Call Forwarding, shouldn't the messages have gone to my home phone's voice mail message -- and not my sister's, since it wasn't her number they dialed? By the way, neither caller had her number, so they couldn't have dialed it by accident.

Everything seems okay today, although I did not set up Call Forwarding.

What could be wrong? My cable/phone/Internet company never heard of that happening. They just told me to make sure I had deactivated Call Forwarding via my web account to make sure.