SMS S138

The term SMS S138 most likely refers to a specific model or type of Short Message Service (SMS) device, system, or protocol configuration. Without more context, it is impossible to determine the exact nature of "S138." The "SMS" part of the designation clearly indicates a relationship to text messaging technology. The "S138" portion could be a model number, a version identifier, a serial number, a configuration parameter within an SMS system, or some other proprietary designation assigned by a manufacturer or service provider. Further investigation into the context where this term is used would be needed to ascertain its precise meaning.