Home # ring busy when call forward is activated

[sawswas]

I had FIOS installed last week and I am having a problem with call forwarding.  After I forward my calls if anyone call my home # and I answer that call its fine.  But if  a 2nd person call my home # while I am still on the phone with the 1st call  they will get a busy signal.  I am forwarding my calls to my cell phone and I have been doing this for years and never had a problem.  Has anyone had this problem?  I tried calling customer service but the hold time is to long.

Thanking you in advance