Skype and DTMF

Does anyone know if Skype supports sending DTMF tones?

I tried a couple of calls last night, using 0844 callthrough providers
to try and reach UK mobiles, and I was asked to enter number after I
already had. I don't think it was any of the other providers involved
in the call, as I've used them before without problems. Thanks for any
info.

andy