I have heard of this issue but have not had any evidence of it occuring on a regular basis
How many tels
R6.0.49 code ?
Analog lines ?
Internal lines or external tlim ?
Digital Lines ?
What type of system ?
How long has it been installed ?
Day 1 issue or just started occurring ?
What is the rev on the bottom of the tels ?
I would also upgrade to R6.0.63 as this is not mentioned in the release notes and work was done on the analog lines .