Solutions:
1. Whether SMS receiving function is normal or whether the SMS center number is correct (the some versions do not need to set the SMS center number).
2. Turn on the “always receive MMS option” ("system Settings" > > "all Settings" > > "Mobile Network" > > "always accept MMS").
3. Ask the operator whether Internet service is activated (customer service should pay attention to the difference between the "mobile Internet" business and the "monthly package". " Mobile Internet access" is a basic business, and generally does not charge.
4. MMS transmission must have the "mobile Internet" function in order to send successfully, but it will not charge traffic fees. Operators charge according to the number of messages.
5. Whether the selected attachment is too large. Operators generally have strict size restrictions on the pictures sent by MMS. Inquire the operators for details.
6. It is suggested to replace SIM card of a different operator card and try again.
7. It is suggested to back up the data and restore factory settings, update to the latest system version, and try to send again.
8. If the above methods do not solve the problem, it is recommended to go to the after-sales center for inspection.