Does the telecom operator server save short messages? How long has it been? One year.

First, the transmission was successful. When the receiver can accept the short message, HLR will inform SMC, which will send the short message and delete it automatically after success. How long to save depends on the operator's settings, generally 24 hours.

Second, the transmission was unsuccessful. SMC will only store short messages when the receiver is full, unreachable and turned off. When the receiver can accept the short message, HLR will inform SMC and SMC will send the short message. This situation lasts for 7 days at most and 7 short messages at most.

HLR (English full name: home location register): the database that HLR is responsible for the management of mobile users. Storing the subscription data of managed users and the location information of mobile users can provide routing information for calls to a certain MS.