Q: My iphone 4s does not go to voicemail it just continuously rings-disconnects and recalls vs. going to  voicemail!

I'm a newbie to iphones so please be patient if this is an easy fix!

Every time someone calls and I miss the call my phone...    

* rings a long time then disconnects and then calls again (shows missed calls) - but continuously rings on their end - never goes to voice-mail.  I'm not sure how long this has been going on because I usually answer - but noticed it last night when someone told me it didn't go to voice-mail.  They said it just continuously rings.  I tried it with my husband's phone and sure enough rang about 14 times (then he hung up) and showed up as 2 missed calls - even though it was just one.

Not sure how long it has been like this - I would always get voice-mails before.

Thank you!