Where does a text SMS go if the receiver’s phone is switched-off?

The transmission route of an SMS (short message service) is not different from that found in phone calls. Whenever a person sends an SMS through his mobile phone, that data or the contents of the message will be first received by the SMS center of the network service provider that the sender has chosen. This SMS center is nothing more but a server that is meant to directing and control SMS traffic, so it is not actually a center that physically appears in the real world.

It is the job of the SMS center or server to contact the network of the receiver’s service provider if the receiver does have a different provider. However, if the receiver has the same service provider as the sender, then the processing would be much faster and easier for the SMS center. Through the contact in the center, the SMS message will ultimately reach the receiver’s mobile phone.

For the sending process to take place, it is important that the receiver’s mobile phone should be switched on. This is the normal procedure that occurs between two mobile phones, but it is noteworthy to mention that the sender’s network does not relay or send the message to the receiver’s phone straight away. The sender’s network or the SMS center first finds out using the receiver’s network if the receiver’s mobile phone is switched on or not. The status of the receiver’s phone is usually checked by the network through the receiver’s Home Location Register (HLR).

Let us imagine a scenario where the receiver’s mobile phone is not switched on. In that situation, the sender’s network will send a request to the HLR of the receiver’s network to pick up the SMS message if the receiver’s mobile phone is eventually switched on. Meanwhile, while the receiver’s phone is off, the receiver’s service provider keeps the message in a “pending” status. How long the SMS message will be kept by the service provider depends upon their policy. There is currently no uniform practice among service providers when it comes to how long they can keep SMS messages, but according to the business policy of most individual service providers, the period of pendency for SMS ranges from 2 hours to 2 days.

What are the types of SMS messages?

Aside from the regular SMS sent by a sender to a receiver, there are also other types of SMS messages that can be received by a person that owns a SIM (subscriber identity module) card and a mobile phone.

The first and most common type of SMS is the one-way SMS, which is the one that is sent by a sender to a receiver. The one-way SMS doesn’t act like a phone call, as there is no possibility of the receiver replying to the message while it is currently at the SMS center. It is called one-way because it doesn’t bounce back to the sender, and the message only goes through one route. Replying to a one-way SMS is possible, although having a conversation with the initial sender via SMS is a lot slower than talking to him or her via phone call or chatbox.

The second type is two-way SMS, wherein the message can be replied by using keywords. For example, if a magazine subscription is about to expire, the company will send you a message asking you if you want to extend the subscription or cancel. In this scenario, the receiver will have a choice of sending a message that has either “SUBSCRIBE” or “CANCEL.” The company’s network then automatically responds and performs actions based on the message you sent. This type of SMS is typically used by businesses that wanted to inform their customers about promos and subscription statuses.

The third type of SMS is called toll-free texting, although it is sometimes known as 8XX or 8YY texting. In this type, a toll-free number with three-digit codes receives messages without being charged. This type of SMS is used by mobile phone owners abroad who wanted to send or receive a text without being charged extra.

Conversational SMS is the fourth type that allows two mobile network users to talk to each other via messaging. However, conversational SMS is different from chatboxes since the former is provided by a mobile network service provider while chatboxes are handled by social media companies. Conversational SMS is often utilized by businesses to have a faster conversation with a client or customer who wanted to ask for assistance.

The last and most advanced type is the SMS chatbot, where a digital robot will respond to the sender without the assistance of humans. SMS chatbots are still currently being developed, but in the future, these AI responders will be able to provide customer service by understanding the situation of the customers while also knowing how to help them.