[n2nov]

Originally Posted by nd5y

A lot of current 2m/440 FM rigs have "paging" functions that can beep or open squelch on a 3 or 4 digit DTMF sequence.

Let's first find out from the original poster what their intended use of this function is. If it's to decode a set unit or group ID code, then your answer fits. If it's to decode over the air repeater control codes or phone numbers being sent to an autopatch, then it needs to be an open ended DTMF reader that is external to the radio like the one that Ramsey Electronics sold.