What kind of power supply are you using for the PIC®?
Does this P.S. have an earth connection?
Is it Switching Power Supply?
Is it the current supplied enough when relays are ON?
Do all relays have Diodes for the back EMF?
Try to have all ground points to one specific point to avoid ground loops.
Are you sure that your Isolation transformer does indeed isolate the Line from the circuit?
Post your latest code. May be something is wrong with the code. Ooh, and what about the MCLR of the specific chip? Is it connected to +Vdd? Check its level.
And by the way, tere is no need to have 2 relays. One can serve as Dial and Hook at the same time.
Ioannis
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