On 2015-07-30, micky wrote:

But one modular jack has black spring wire,
and modular plug has one black contact.

Need gold connections.

Been there, wore out that t-shirt.

Got an outside line (POTS/DSL) from my point-of-access (PA) to house.
Couldn't find a single line long enough so connected two lines with
dbl-female union. Over the last Spring, lost both phone and internet
connectivity several times. Each time it was mold ("black") on the
contacts of the mid-line union.

My solution: old tooth brush and WD40 (which is a water displacement
(WD) formula, not a lubricant!). Hosed all connections w/ WD40 and
scrubbed mold out with toothbrush. Worked well in dead of
rainy-season as a quick-fix, but finally hadda buy a new union.

HTH
nb