Things Behind SMS Web Services In a Short Story

Short Message Service (SMS) is defined as the transmission of short text messages to and from a mobile phone, fax machine, or an IP address. These plain text messages have a maximum limit of 160 alphanumeric characters, and cannot have images or graphics. Let’s consider that a message has been sent from a Web site or application that offers SMS services.
The message is routed by the service to the user’s cellular network. It is received by a Short Message Service Centre (SMSC), which directs the message to the recipient’s cell phone.
The SMSC sends an SMS request to the Home Location Register (HLR) to find the roaming customer.
Once the request is received by HLR, it responds to the SMSC with the subscriber’s status (active or inactive) and roaming location. If the status is inactive, SMSC stores the message for a specified period of time. When the device is active, the HLR sends an SMS notification to the SMSC, which then tries to deliver the message.
SMSC uses a Short Message Delivery Point to Point format for transmission of the message to the serving system. The system contacts the mobile and if it responds, SMSC tries to deliver the message.
When the message is received by the user, it is categorised as ‘sent’ and is not sent again. And if you have a mobile, the moment you receive an SMS message, you get two short beeps (or any other sound that you may have pre-configured), to indicate that you have received an SMS message. So, go ahead and read that message.