The idea of Peter is very appealing, since there is minor voltage change, and a large current change when a parallel set is connected to tel line.

Well, let's decide that I should measure the loop current flowing into my telephone set.

Now I have following queries and need further guidance.

1) Loop current will vary from line to line, so there is no hard and fast rule that "abc" should be the minimum loop current and if not, some parallel set is connected on the line. (because it is possible that one line provides 40 mA, and other is giving just 18 mA, so in case of 18mA, We can't say that there is a parallel set.)

2) If I measure loop current upon off hook, and store it in RAM, and then through out the call, I observe for any large change in this loop current (off course for a specific time)then this method would work well.

3) But what if a parallel set is taken off-hook first, and then my phone is taken off hook, now there is no way to detect the parallel set (as described in 2).


Thanks Peter and Mehmood.

Any other intelligent idea????


Regards

IJAZ