Most phone lines in the U.S.A. don't support DP ("pulse" dialing), but only DTMF ("tone" dialing); most European phone lines do support it. But how can you tell?

Here are a few ways, going from the blindingly obvious to the subtle:

  • Connect a rotary dial telephone and see if it works.
  • Some push-button phones can be switched to DP. The switch will say DTMF/DP, or maybe just have a picture of a musical note on one side (DTMF) and a pulse waveform on the other (DP). Switch your phone and see if it still works.
  • Pick up the handset and give the cradle 2 rapid taps. On a DP switch, this will be interpreted as dialing either a 2 or a 1; one result of this is that you've started dialing a number, so the switch terminates your dialtone (you might hear a rapid pip to signal that this has occurred.

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