Phones are certainly not authorized In the temple. There's a facility locker supplied by the temple committee for devotees to post their telephones though entering the temple. One story found in the Tang-era monk Yi Xing's commentary on the Mahāvairocana Tantra portrays Mahākāla as a manifestation of the buddha Vairocana https://jasperbauco.activosblog.com/26343802/the-2-minute-rule-for-mahakal