I have a project in mind that would dial a phone number on a POTS phone. Assuming I can generate dtmf dialing tones (perhaps even with a wave shield using downloaded tones if necessary) what do I need to be aware of in terms of connecting to a phone line? I'm sure there's voltage levels to be concerned with, but I'm not sure where to start looking or what to do to protect the arduino.
For the purposes of the project, I don't need to lift the receiver within the arduino; that will be done physically by the caller.
I'm still a relative beginner with this, so please excuse me if I'm missing something obvious.