The provisioning process to activate the number does not in any way effect the voice communication, IVR, plan, carrier or any aspect of the voice service. The SMS capability works “over the top” of the voice platform. This capability has actually existed for a number of years (think Google Voice) but is just now coming to the forefront of B2C communication.
The technical explanation: Every number that is text-enabled is associated with a SPID (Services Poivider ID) who issues the cell phone service – also known as a carrier. If we text-enable your mobile/cell phone number, you could send/receive messages on our SPID, but then you will lose the ability to send/receive messages through their carrier. In other words, this means your phone loses it typical texting capabilities as it’s impossible to have two SPIDs sending/receiving messages.