Sangoma introduced free SMS Text Messaging with Switchvox Cloud in version 7.6.3. This feature is automatically available on all SMS-capable phone numbers within the Switchvox Cloud service.
...
However, it is worth noting that Switchvox allows flexibility to change this default configuration. That may be useful if you do not want a user to be able to send SMS text messages, or if you want a text messages to be handled by a different user/extension than the one to which voice calls are routed (for example, when voice calls are sent to an IVR or Call Queue). This is discussed further in the Changing section below.
SMS Behavior with Upgrade to Switchvox Cloud 7.6.3
...