SMS Fallback
The Enterprise Number Archiver server has a fallback option to send a message
as an SMS in case the IP message was not received by the app.
If a message is not received by the app in case of no data network connection
between the app and server, the system retries to send the message twice. If
the retries fail, the app defaults to SMS fallback. In this scenario, SMS charges
apply according to your network plan.