ISSUE: Moderate to severe static on rainy or even very humid days.
parties on both sides have difficulty hearing. Also, unable to connect
to Internet. When things dry out everything is OK.

Verizon guy tested jacks and inside wiring and said they're OK. He
found minor "short" problems on the three phones, readings of 10, 10,
and 20.

His diagnosis: Phone units with minor faults when weather is dry
become severely problematic in wet weather. In other words, the
problem lies with the phones, not with any wiring or jacks.

However, he was unable to answer these questions:

1) Are you saying that moisture and humidity get into the phone units?

2) If so, how come there was no static when we tested the phones
during the rain, using the interface box on the side of the house?
Testing revealed a nice, clear dial tone. Static occurred only
inside.

He shrugged his shoulders and left.