Bluetooth Connection Issue

I recently bought a sony ericsson s710a. I was able to get it to link up with the prius, and it worked fine for a couple days. Now I can not get it to connect at all. When I bring the phone in the car the bluetooth icon on the phone displays the two little arrows as if it's connected, but when I try to make a call through the car it says something like "check phone".
So I tried removing the phone registration from the car altogether, and removing the car registration from the phone, basically starting from scratch. Now when I try to reregister the phone the phone will recognize the car, but the car just stays on the screen where it's displaying the passcode, and never recognizes and registers the phone. I was wondering if you all had any suggestions.
I'm thinking maybe I got a faulty phone. I'm hoping it's not something wrong with the bluetooth in the car. I would have tried to return the phone by now, but I bought it online so it will be a bit of a pain.

 

Yes, I reentered the passcode. This is when the phone said it had successfully connected with the car, but the car remained on the screen that displays the passcode. I also tried changing the passcode in a random attempt to get it to work. No luck with that either.

 

<div class='quotetop'>QUOTE(wstander\";p=\"115820)</div>

Hmm... when I originally had it working for a few days, I did not have to use any special "car settings" through the phone. I will check out their website as you suggested and see what I find though. Thanks for the suggestion.

 

So I just checked out the sony ericsson support site for the s710a phone, but did not find anything helpful.

 

Yes, I really like the phone aside from the bluetooth issue. I did a lot of research on the bluetooth enabled phones that Cingular offers before I decided on this one. The main reason I decided to upgrade my phone to begin with was so that I could use it with my car, so this is a huge bummer.
I checked out Cingular's website as well. The best I could find is a tutorial on how to turn bluetooth on, and the pictures shown don't even match the s710a. So much for that.
If I can't figure something out soon I'm going to take it over to the Cingular store and see if they will let me exchange it for another one.

 

So I went to the Cingular store today, and they were nice enough to let me borrow a different s710a to try out. When I took it out to my car it worked fine, so I was thinking it was my phone at that point.

However, when I took my phone back out and tried it again it was now working as well. I think it is what you suggested that did it - rebooting the phone. I had tried removing the pairing information from both the car and the phone, but had not tried rebooting the phone to this point. So I'm thinking when I took the battery out of the phone to remove the sim card, that's what did it. I just hope I'm not going to end up having to reboot my phone every time I want it to connect to my car.

Thanks again for the advice everyone, and I hope this post will be useful to people in the future. I will try and check back in and post a progress report of how the phone is working over the next week or so.