Aastra 9133i phones, blf causes them to ring once

I have 5 9133i phones connected to my Asterisk box. All works great, except for the single ring all phones make when one phone gets a call. If I call from phone to phone, all phones will ring one, then the phone I am calling continues to ring. I have two phone numbers, each rings different set of phones. When a call comes in for one set, all the other phones should remain quiet but they give one single ring. Very annoying. Any ideas how to stop this? I love the blf feature so each person can see who is on the phone, I just can not have all this extra ringing.