* Regression tests for the messaging mode on sendSms()
* Let sendSms() name the esm_class messaging mode
* Document the messaging mode option and the decision behind it
* Name the constants move for migrating consumers and share the refusal's value naming
* Cover the messaging-mode refusals through submitSms()
* Refuse transaction mode and a report under datagram mode on sendSms()
* Narrow the mode checker and name the default mode once
