@Distressed how many instances of the charge do you have?
If it is only one or two and between 9-5ish and you don't think it is anyone in your household that is calling the speaking clock, it may be an engineer checking the line. They really should not do it, but it can happen.
On the other hand if you are getting lots of calls at all times in the day, a faulty line can be the cause - you may also notice a noisy phone line and a reduction in your broadband speed.
HTH
