Actually, sharing with you all, but English, what can I say?
this started after the famous flooding here - covered in the national news. PROBLEM: outgoing calls: NO problem, clear voice line and dial up modem within 95% of 'normal' [seen slower rates before with damp weather] incoming calls: the ring sounded anemic, like a single tinkle, not to be repeated. Pick up phone, and someone was there?! albeit the connection sounded like old fashioned long distance.
FAILED SOLUTION: at first I thought telco must have a flooded building nearby so called telco supplier, Century Link, Operator said sounded like a crossed connection. she confirmed the possibility by saying outgoing wouldn't notice, but with incoming the office tries to connect to two lines. Put high priority on repair and someone was driving around here the next day. The technician probably checked a lot out first, then came to our building and left. Later I called in, the repair ticket said FINISHED determined to be inside our building, bill the customer $85 !!!????
And yes. the line worked after the technician's visit; BOTH ways ?! I know all he could do is disconnect, test, and reconnect.
Regarding THAT solution, I was livid to have the telco supply a potential scenario of responsibility, THEN turn around and bill me for 'fixing' it, claiming its me. Keep in mind the phone line now works. After a few calls to Century Link , and convincing them I was misled by their employees as to the source of the problem, and the fact that it now works with whatever their employee did; they reversed the charge. [I'm in Electronic Design and cannot even fathom a piece of electronic gear that could duplicate this effect, well not without some effort anyway.]
PROBLEM AGAIN yesterday, the problem came back with a vengeance! outgoing, no problems. Incoming, tinkle ring and poor voice connection. Called the Operator to 'test' the line with a ring back [hang up, listen for ring, no matter what pick up line within ten seconds to reconnect to Operator] This time the phone line was completely dead, no microphone feedback! About an 1 1/2 hour later, phone line worked again for outgoing. Tested incoming, and again a dead line ?! Wow this is strange. Checking around, within 1/2 hour, no dial tone, but would get that screaming tone as a precursor to "hang up your phone" ??!! Very weird.
SOLUTION Thought I'd 'pretend' problem was in our building, so removing the break out panel for the phone system to our whole building found the distribution bar for all the wired telephone outlets, thought I'd start to check AND! one of the wires for the incoming telephone cable coming into the bus LIFTED OUT OF ITS COMPRESSION SLOT!!! The wire oddly was dull showing a film of corrosion, pressed the wire back in and voila! Everything works again.
CONCLUSION Evidently, the connection had been slowly sliding out of the compression slot and the poor connection worked for the low current OFF HOOK status and the low current ON HOOK status when making an outgoing call. BUT, when confronted with that 90V ring tone, the higher impedance must have played havoc, because it even caused a poor voice connection.
I don't undertand the exact mechanism here, but I share for those of you who may have had weird problems.