by NudgeNudgeWinkWink » 05/27/2019
1st ring good, 2nd ring bad? Interesting.
Caller ID info usually arrives between the 1st and 2nd ring. At least it used to with the old POTS lines. I don't know when Voip sends it.
Any chance you've somehow set the "naughty" phone to have all your incoming calls assigned to a "group" with a different ringtone?
Page 29 of the manual for my KX-TG4031C says:
Group ringer tone for phonebook.
This feature can help you identify who is calling by using different ringer tones for different groups of callers. When adding an entry to the phonebook, you can assign it to the desired group (page 17). When a call is received from a caller assigned to a group, the ringer you selected for that group rings after caller information is displayed.
I played around with it for a few minutes, but I can't figure out how to assign a tone to a group. Maybe my version doesn't actually allow it. Does yours?