How do I know that the other party's mobile phone is really down?

1. If the other party has set up call forwarding and the call is forwarded to the stopped number, making a phone call is not an ideal way. \x0d\ When you call the other party's telephone system, you will still be prompted "The number you dialed is out of service", but the other party is not out of service at this time. \x0d\2。 It is suggested that you can send short messages to each other and start information reporting at the same time. \x0d\ If the information report status is normally displayed as "Delivered", it means that there is no downtime. \x0d\ This is the only solution when you don't know the service password of the other party and don't want to make a phone call.