Resolution firmware patch for MT5692SMI, 1.01K. Upgrade will require the AT** flash method.
Noted in Resolution 5031075: RING detect from German analog phone line
This version of firmware remains available for the following issue:
Using the MT5692SMI (.R1) product with 1.01L code, it is noticed in certain conditions/circumstances where the RING is no longer being detected, whereas it was previously being detected with the 1.01J version of code.
Issue initially noticed on standard German analog phone lines, however, could apply to numerous variances of line conditions.