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Why does SMS can only send no more than 160 characters?

77-2801-1-PBShort message service (SMS) is a system where users can send short text messages between mobile phones. In the Latin alphabet, a message that can be sent is limited to the maximum of 160 characters including spaces. This limitation is the result of the SMS operating system itself. Instead of using the main system for telephone communication, SMS using a channel that is designed to send small packets of information between cell phones and cell towers.

This simple channel was chosen as the basis for SMS because it is simple and easy to be implemented. As known, the phone is supported by a network of towers that are responsible for transmitting the call. Cell towers continue to communicate with a compatible phone using a frequency called a control channel. The control channel is used to convey information about the location of mobile phones and towers, once used to manage calls. In contrast to the channel for voice calls, SMS requires only a small exchange of information. When the mobile phone network provider decides to provide the transmission of SMS services, then the system is easy to be implemented.

To set up an SMS service, which is required as the addition of Short Message Service Center to receive messages and forward them to the right tower at the right time. The system is designed by an organization called Global System for Mobile Communications (GSM). Previously, the GSM has analyzed the usual types of messages sent and concluded that the service is only sending 100 to 200 characters are still considered useful. Limited by hardware that only has a capacity of 140 bytes or 1120 bits; they devised a system that can encode characters with the size of 7 bits per character. This process produces a maximum transmission size of 160 characters. If needed, users can actually send the message by combining a group of SMS. However, the limit of the individual package would be reduced to 153 characters, because each packet must contain the metadata to indicate linkages with other messages.

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