Do We Require MOBITEK SMS Engine ( Enterprise Edition)?

We would like to know, based on our deployment diagram (refer below), do we require MOBITEK®  SMS Engine (Enterprise Edition)?

Yes, it is highly recommended to use MOBITEK®  SMS Engine (Enterprise Edition) as you need to allow your remote site to access the SMS Gateway.
InboxFor remote site to access the SMS Gateway, it is best to use SQL database instead of Access database.