Hi sus_22. Please make sure to update your APN settings by following the below values:
1. Press "Settings"
2. Select "General"
3. Select "Network"
4. Select "Cellular Data Network"
*if this option does not appear, the handset is not Jailbroken
Jailbroken iPhone Standard "Stock" iPhone
The following fields will appear:
• Cellular Data
• APN: att.mvno
• Username: leave this field blank
• Password: leave this field blank
• MMSC: http://mmsc.cingular.com
• MMS Proxy: mms2.tracfone.com:80
• This IP Address must include the MMS Port; otherwise it will not work on the iPhone.
• MMS Max Message Size: 1048576
• MMS UA Prof URL: do not make any changes to this field
• Make sure to delete the current APN on your phone and reboot
Please make sure that your MMS is also turned ON. Navigate your phone to Settings>Messages>MMS Messaging ON. Let me know if that works. Thanks!