Please check the settings of your phone and ensure that it has these details.
Your phone may not require the MCC, MNC or APN Type.
Restart your phone after setting up the MMS. Last resort is to do a 'network reset' on your mobile settings.
An article is also created about MMS setup guide.
Note: Some options to send an MMS is to top-up the prepaid balance of at least $10. Option is to change the plan as well to the one that includes unlimited MMS.
Let us know how it goes!