Airport Extreme Dial Up Issue

[Aki]

I have had my Airport Extreme Base Station since last March. We have been using it to share a dial up connection bewtween two Power Books. Two days ago the modem became unable to connect to the internet. It says that it is dialing but gives up before the connection can be made. I have checked the phone line and am able to connect using the modem in my powerbook. The connection seems to be taking a slightly longer time to connect than usual but it does work. I have reset the base station several times but the problem still remains and we are unable to use it to connect to the internet. Any advice or suggestions would be greatly appreciated.