Volvo XC70 (BJ2008) doesn’t like iPhone 3G (Bluetooth) anymore? Why?

Hello dear community, I hope to get a little help here for my problem. For a few days now my Volvo Bluetooth hands-free system (directly from Volvo) doesn’t want to work with my iPhone 3G anymore. The whole thing has worked more or less smoothly since 1 year. Last time I went on a longer journey everything went, suddenly it couldn’t connect to the iPhone any more. Now I tried to do that again. First of all he didn’t find anything in the search for the device at all. Then when I was in the Bluetooth menu of the iPhone (should apparently help), I could connect, well, at least half. I had to enter the pin on the car then, and then he tried to connect it. On the iphone then I could find in the device list “My Car” as well as connected. On the center console of the Volvo stands “no connection”, although it indicates above so dashes about the reception. But there is no way to make a phone call again etc. I have tried this all the time, but so far I couldn’t find a solution, why it is not possible to make it work again.