Nortel Networks M3110 - Manual (Page 184)

Page 184 of 504 M3900 installation and configuration
553-3001-367 Standard 3.00 August 2005
Reliability
Reliability is measured by the Mean Time Between Failure (MTBF). The
MTBF ratings for M3900 Series Digital Telephones are shown in Table 29.
Table 29
M3900 Mean Time Between Failure ratings
Set MTBF Return rate per year
M3901 250 years 0.4%
M3902 200 years 0.5%
M3903 150 years 0.4%
M3904 93 years 0.23%
M3905 100 years 0.25%
Key-Based Accessory
module (KBA) 500 years 0.2%
CTI Accessory (CTIA) 50 years 2%
Power supply 30 years 3%