Had the same error and had read this post and added a subject but still got the same error.
Found in wip_mms.h - line 206
- @note Options WIP_COPT_MMS_FROM and WIP_COPT_MMS_SUBJECT are mandatory.
-
\n\n The option WIP_COPT_MMS_MESSAGE_CLASS only supports -
WIP_MMS_MESSAGE_PERSONAL for many operators. -
\n\n The option WIP_COPT_MMS_PRIORITY doesn’t support WIP_MMS_PRIORITY_HIGH.
The From number is manditory.
Added AT+WIPOPT=8,1,2,91,“0432112345” and WIP now sends the MMS
Hope this helps
Noel