I've got some SPA5xx phones working on a Fritzbox 7270. So far I got erverything running fine except one major problem: Once I have initiated a call to a e.g. service hotline which wants me to select the appropriate contents by dialing a number, I can't do so. Well, I can very well dial, and I get the sound of the key pressed, but the automtic menu system of the service hotline won't recognize the dialed number.
I hope I could make my question clear, since I'm not a native English speaker.
I went through tons of forum questions but just cannot find a solution.