My iphone CALL FORWARDING was hijacked and calls sent to unknown number

You might be experiencing this same problem and not know it. I didn't know. I missed phone calls because they were begin forwarded to an unknown number (that I DID NOT enter into my phone). I had people send email to me saying that every time they called me they got a message that said my call was being forwarded to an answering service. My phone did not ring and the caller was never able to get to my voicemail because it was being forwarded. Sure enough - looked in my iphone settings and found a phone number listed under the CALL FORWARDING setting. Please check your iphone. Your calls might be hijacked! Why won't apple fix this? Check your phone by going to SETTINGS > PHONE > CALL FORWARDING and make sure there is NOT a phone number listed there.