Hello,
If you are on the SMSC Settings page, the built-in Help context provides some helpful details about the different options you have when setting it up.:
Configure SMS settings to enable sending text messages.
Select a method of sending SMS messages.
* The Modem option requires you to configure connection parameters for the modem to connect to the SMSC server.
* The SMS Sender option requires you to obtain and register the serial number and password.
* The Other SMS Sender option is a third-party SMS sender. The access method includes custom access and general configuration access. General configuration access is only applicable to third-party SMS senders. The interfaces provided are Web service interfaces that use HTTP. System sends simple HTTP requests based on interface requirements to complete docking.
There is definitely an option there for using HTTP, and I don't think it should matter if the gateway is hardware or software-based. However I'm honestly not too familiar with setting up SMSC in IMC.
Would that work for you?