I've set up my Tiscali account so that I can do this - they give you an 0870 number and you get the faxes in your email inbox, which is great. But in order to send faxes I have to pay a minimum of £10 into my account with them, which would allow me to send 100 pages - and as I only use faxes to communicate with my mum (and this is only temporary anyway), I'll never use that up.
I got a piece of software called PhoneTools free with my PC but it's now a bit old and doesn't recognise my broadband modem.
Is there another piece of software I should try - preferably a freebie or trialware or something? Any other suggestions?