Mr RB
Well-Known Member
Hi, I am contemplating making a auto phone dialler for standard landline telephones. I can do the DTMF generation in software using a PIC to dial the outgoing number, and can do the off hook control easy enough with a transistor to pull the line low.
Does anyone have experience building one of these, specifically regarding detecting that the person receiving the call has picked up the phone?
All I can think of is to detect the ringback tone as the phone is ringing, then wait for an absense of ringback tone for X seconds. It's not a pretty solution as the PIC will have to detect and interpret the sound, with the ring pauses, and when the phone stops ringing it will most likely be replaced by other sounds like the person talking.
Is there something I'm missing that would be an easier way to detect the person has answered? Any changes in line voltage or other easy way to detect?
I appreciate any help.
Does anyone have experience building one of these, specifically regarding detecting that the person receiving the call has picked up the phone?
All I can think of is to detect the ringback tone as the phone is ringing, then wait for an absense of ringback tone for X seconds. It's not a pretty solution as the PIC will have to detect and interpret the sound, with the ring pauses, and when the phone stops ringing it will most likely be replaced by other sounds like the person talking.
Is there something I'm missing that would be an easier way to detect the person has answered? Any changes in line voltage or other easy way to detect?
I appreciate any help.