How SMS gateway works
In case of, if you send and receive bulk sms messages, it is highly recommended to transfer them via the Internet. (Figure 1) Through the Internet (or over a personal IP network (VPN)), it is feasible to connect directly to the GSM operators’s SMS Center (SMSC). The SMSC’s manages the receiving, storing and delivering of the SMS text messages in a GSM telephone network. It provides diverse benefits of connecting directly to the SMSC.
In a short-term of time immense amounts of SMS messages can be sent or received. It is possible to change the sender's phone number. You can track the status of the SMS messages with notification messages.
It is a so much better way instead of using a GSM device (modem or phone) which is in connection of a computer with a phone-to-PC data wire, because it’s affordable, faster and has more reliability.
Bulk SMS sending over Internet to directly to the SMSC is less expensive, faster solution and has more reliability than connecting a GSM device to PC with datacable.