"Gil Kloepfer Jr." <gil@limbic.ssdl.com> (06/06/91)
I've recently noticed a problem I originally thought was CO-related, but am now thinking is CPE related, and I need to know about the following scenario from those "in the know". To start, I know (from talking to the phone guy who came to install my lines) that I'm on a AT&T #5ESS. The situation is this: You call your telephone line, and you "hear" one ring, then a busy signal. Your phone line at home is DEFINITELY free, that is nobody is using it and it SHOULD be clear. The line is NOT on a SLC-96, so it shouldn't be a problem where the line isn't accessable for some reason. What I have found is that a bad phone can busy the line out in this manner by seemingly "picking up" the phone RIGHT BEFORE the first audiable ring is heard on the CALLED line (I made it happen in this manner). Here's my problem: I originally had this problem once with a bad phone. Now I'm having the same problems with a device I built to decode the different ring patterns for my personalized ring numbers. The device is essentially a resistor (15K) in series with a .22uF capacitor and the AC input to a bridge rectifier. The output of the bridge rectifier feeds a 12V zener and RC filter to smooth out the signal, and ultimately an opto-isolator. I know I should technically be using a FCC certified DAA, but let's not get into that discussion here. Can anyone think of a reason why this circuit should produce the results I describe? Does anyone have specs on what kind of current drain a typical residential subscriber line can tolerate during ring before an "answer" is detected? Can a proliferation of these .22uF/15K resistor combos produce some kind of capacitive "kick" which the CO thinks is line trouble and/or something using the phone line (and what are the specs for this)? Thanks in advance for any info y'all can provide! Gil Kloepfer, Jr. gil@limbic.ssdl.com ...!ames!limbic!gil