Not all phone carriers support MMS messaging.  

Any MMS message that is created will also include a non-MMS version of the message for the carriers that do not support MMS.  The character limit of the non-MMS message is adjusted by 30 characters to allow for a system-generated URL that provides access to the MMS content (i.e. graphic, video, audio file). This is why the default non-MMS message allows for 84 additional characters instead of 114 characters.