What does a Telcordia-certified life claim?

It means the life figure was demonstrated under Telcordia's telecom test methods rather than projected from an internal model. C&D publishes the TEL series at a certified life exceeding 10 years, which is the number network operators can put in front of an auditor. Real service life still depends on temperature and float discipline at your site.

Do I need the high-temperature version instead?

Only if the environment says so. In a conditioned central office or a cabinet that stays near 77°F, the standard TEL build carries the duty at a lower cost basis, and buying pure lead headroom the site never uses helps nobody. Where the enclosure bakes in summer or the site skips cooling to save power, the TEL-HT line exists for exactly that, and we will tell you plainly which side of the line your site sits on.

Is this battery safe for an occupied equipment room?

Yes. The TEL series is sealed AGM VRLA: the electrolyte is absorbed in the separators, there is nothing to spill and nothing to top up, and the case material carries the UL 94 V-0 flammability rating. Standard ventilation practice for VRLA strings still applies, and your install code has the final word.