Local officials are urging residents who use Comcast for their home telephone service to add their contact information to the town’s mass notification system, which is used to spread information about emergencies and other events. Those who do not opt into the system will no longer receive the alerts. Comcast notified town officials late last month that it had removed the home telephone numbers of customers who had not opted into the Reading Community Alerts system. It is uncertain whether, how, or when those numbers will be restored to the system, according to the town’s announcement. Comcast customers who have already signed up for the system do not have to do so again. For more information, visit www.ci.reading.ma.us, or call 781-942-6726.