Why is SMS 160 characters?

SMS system is designed for short bursts of data services such as numerical pages. To avoid overloading the system over the standard forward and reply operation, the inventors of SMS agreed on a maximum 160-character size of the message. 160 characters, but is not fixed. Limitation of extension may vary depending on network, phone model and wireless service provider. Some phones do not always allow time to write a 160 character limit has been reached. You must send the message before continuing. However, a number of services will automatically break any message that is sent in packets of 160 characters or less. So, you can write and send a long message, but will be delivered as several messages