Modem - no signal

I have an external modem fujitsu fdx340 that I have had for a few year which provides my external broadband connection - one lead from the unit goes straight into a connector ('C') which plugs into the phone point. the other connection ('C') goes into my pc.

Out of the connector ('C') above I have a splitter which goes to a telephone.

Everything was OK last night now this morning when i try to connect to the internet it says there is no signal. I've checked the connections and nothing is loose. The modem has a green light which shows that the power is on. My telephone line works ok.

The data light on the modem flashes intermitently when connecting to the internet when using my dial up connection. My pc has an internal fax/modem for dial up connection purposes.

Can anyone please tell me what the problem might be and how to resolve it?

Thanks