I was getting this error after mmsd decoded the initial WAP notification. This was on Ting, a T-mobile MVNO, which does not appear in my mobile-broadband-provider-info database. The problem was that I did not have a MMSC defined. I believe ofono should get this information from the provider database. The following is a workaround using a modified ofono test script.

Append the following to test/create-mms-context:

        if len(sys.argv) > 4:
                context.SetProperty("MessageCenter", sys.argv[4])
                print("Setting MMSC to %s" % (sys.argv[4]))

Then, run the script

$ test/create-mms-context wholesale "" "" http://wholesale.mmsmvno.com/mms/wapenc
Created new context /quectelqmi_0/context2
Setting APN to wholesale
Setting username to
Setting password to
Setting MMSC to http://wholesale.mmsmvno.com/mms/wapenc