Call Forwarding is not allowing me to call home.

I have my account set up to forward calls to my cell phone.  This has been useful to allow me to answer my phone even when we are away from the house and has been working for years.  Within the past month, however, when I try to call home from my cell phone, the call no longer goes through.  The answering system answers right away and asks me for my password.  The home phone rings only once and then stops.   What changed?  The only way I can  call home on my cell phone is to turn off call forwarding entirely, then it works fine.  How can I get this feature that I have liked for years to work again?  Thanks!