One problem of SMS messaging is that SMSCs developed by different companies use their own communication protocol and most of these protocols are proprietary. For example, Nokia has an SMSC protocol called CIMD whereas another SMSC vendor, CMG, has an SMSC protocol called EMI. We cannot connect two SMSCs if they do not support a common SMSC protocol. To deal with this problem, an SMS gateway is placed between two SMSCs. This is illustrated in the following figure. The SMS gateway acts as a relay between the two SMSCs. It translates one SMSC protocol to another one. This way can be used by two different wireless carriers to interconnect their SMSCs for purposes such as enabling the exchange of inter-operator SMS messages.

Figure 1. An SMS gateway acts as a relay between two SMS centers.

Besides wireless carriers, content providers and SMS application developers may also find an SMS gateway useful. Let’s consider the following situation. Suppose you are the developer of an SMS text messaging application. To send and receive SMS text messages on your server, one way is to connect to the SMSCs of the wireless carriers. Different wireless carriers may use SMSCs from different vendors, which means your SMS text messaging application may need to support multiple SMSC-specific protocols. (This is illustrated in the following figure). As a result, the SMS text messaging application’s complexity and development time increases. Read the rest of this entry »