Internet Telephone

I have a headset with microphone used in internet cafe connected to my PC.
How do I use the internet on my PC connected to broadband from BT as a telephone service?

Simply connect a digital phone calls to your BT Hub ... Free depend on which option you are on ... check your contract
usually in the evening after 18 hours .... and weekends are free from landlines .... you have to pay for calls to mobiles ... recheck contract
If as suggested, you want to use Skype .... theres 2 options ... (1) SkypeOUT costs .. You about 1.4 pence per minute to landlines local and international ..
(2) SkypeIn calls .... are free, but both you and the other party to buy an annual subscription costs around £ ... 10-15 per year
So unless you intend to make many calls, I think you are using SkypeOut cheaper ... place for you .. just read all before you decide bumpf hope thats ... aid

You can try calling them and asking this question. Seems to me to solve a problem with your ISP. That said, you can try using Skype yet.

Download Skype (free) and get an Internet phone or webcam with microphone. Provided the person you are calling has a similar configuration, all calls are free (and good)