Support OOB (XEP-066)
To work properly with JMP XMPP to MMS images chatty needs to support XEP-066
https://xmpp.org/extensions/xep-0066.html
For this it also needs to permit you to select (or by default use) XEP-0066 in their XEP-0363 implementation, per https://xmpp.org/extensions/xep-0363.html#reqs