Why can SMS be sent, but MMS is "waiting"?

This is very important. Whether it is SMS or MMS, sending is such a process. You use your mobile phone to send it to the information center in your area, which is uplink. Then the information center judges whether the other party's mobile phone is in this area, if not, it will be forwarded to other areas for information processing, and then the local information center will send the jargon to the designated mobile phone, which requires a process of information transmission. There are several possibilities for your question. First, the other party's mobile phone is not in the service area. Although your information has been submitted successfully, it has not been successfully downloaded to the designated mobile phone. Second, when the mobile phone is turned off, telecom operators often keep information for 24 hours. Once the user is turned on, it can receive normally. Of course, the other party's mobile phone must have the conditions to receive MMS.