Why should SMS be changed to MMS?

When sending a short message, the prompt will be sent by MMS, which may be caused by the following reasons:

1. If there are more than two short messages (that is, 130 characters or more) when the client sends a mobile phone self-writing short message, the system will send it by MMS;

2. Is it a font format? No.9 song style? If the font setting is changed, it will also be sent by MMS. Note: Only QQ2008 New Year's Eve edition has been changed to NO. 10 and Song Ti, other versions remain unchanged.