Receipt of SMS messages from a previously unknown or unexpected long code is no different than receiving a message from a previously unknown or expected email address. At best, it may be recognized; however, at worst, it could be a phishing attack. There is no legitimacy. With SMS Short codes, you have some measure of confidence that the message is legitimate as the sender is likely recognized. In fact, if an organization is sending important, time sensitive messages such as 2FA codes, then we would recommend that the originating address of the SMS messages should be an easy-to-remember and recognize short code.
Why is it important that SMS messages are routed correctly? The global SMS ecosystem consists of separate, logical Application-to-Person (or A2P) connectivity network – one where mobile network operators (MNOs) have approved, and in many cases, monetized, this type ofmostly commercial and non-human generated traffic. Traditionally, the A2P network uses separate connectivity from the general conversational or Person-to-Person (or P2P) connections. Thereasons for this are numerous; however a significant reason is that it helps to control spam andgrey routetraffic over the P2P networks.