What happens with SMS when recipient has no signal?


New Member
Oct 3, 2008
My wife and I (both iPhone users) live in New York City and are often in the subway, where there is no signal. Several times, I have sent her text messages while she is presumably in the subway. It seems that they are then not delivered to her at all until another text message happens to be sent. At that point, both the old and new message is delivered at the same time.

Is this the way it is supposed to work? How are text messages delivered if the recipient is out of signal range when it is sent? This doesn't seem right. Thanks for your help!


New Member
Jul 10, 2007
Philly Burbs
It's queued up and delivered later. I don't know the expiration time, but it's probably more then a few days. It could be that the delay ends up hitting the same time as the new message.



Sep 22, 2008
Tucson Arizona
A Google search lead me to an article by Mr. Joe Macon

Short message service (SMS) is a wildly popular feature available on most digital mobile phones. SMS allows users to send short messages to other cell phones. These short messages are called text messages. SMS was invented by a Finnish civil servant named Matti Makkonen. Many people understand what SMS is, but few understand how it actually works.

In SMS, messages are sent with a “store-and-forward” mechanism. The messages are sent to a Short Message Service Center (SMSC), and then relayed to the intended recipient. If the messages do not reach the recipient upon the first attempt, then the SMSC will try again. It is important to understand that SMS delivery is not guaranteed. Many messages cannot be delivered, but the delivery is called “best effort.” The amount of attempts to send a text message varies with the company.

SMS messages are transmitted via SS7 within the standard GSM MAP framework. SMS messages have a certain payload length. The signaling protocol is precisely 140 bytes. In simple terms, SMS messages have very constrained character limits. This is why messages are sent in “txt speak.” Text speak is the practice of shortening words and phrases in order to fit messages into the allowed amount of bandwidth. SMS messages cost different amounts in different countries. In the United States, the average message costs 10 cents.

Text messages do not always have to be sent from mobile phone to mobile phone. AOL Instant Messenger has an option that will send instant messages to a cell phone. Additionally, there is a widget available for Mac OS X Tiger that will allow a user to send text messages to a cell phone from the dashboard. SMS messages can also be utilized to give news alerts. Additionally, SMS messages can be used to give sports updates and statistics. In this way, SMS messages are very versatile.

Technology is constantly evolving. SMS services prove that communication is becoming broader and easier. Technologists predict that SMS service will advance such that the service will be more reliable, and be able to store more data for the purpose of transmission.


New Member
Sep 18, 2010
It used to be that an SMS (text message) would be stored in the system for 72 hours waiting until the phone was turned back on and authenticated itself with the system.

If the phone was powered back on beyond that time, the intended message would be cleared from the system and not reach (or terminate to) the recipient's cell phone.

That's why, for example, when you land from a flight, or come back into an area of signal from a hike in the mountains, any lingering messages will come through.