May 4th, 2011

Text Messages are Faster than Email, but not Instantaneous!

We have discussed how email messages should not be expected to arrive instantly.  This naturally brings to mind “text messages” (aka SMS messages) that people send to their cell phones.  These are commonly expected to be delivered “instantly” — but that is also not always the case.  While text messages are generally very fast, and usually more quickly delivered than email messages, they are not always “instant”.

A few fun facts about text messages to set the stage

  • Text messages are not guaranteed to be delivered. Text messaging is a “store and forward” technology (kind of like email) that depends on various cellular carriers and their networks.  As such, individual messages are not guaranteed to arrive at their destinations.
  • Most cellular carriers provide “email to SMS” gateways that allow email messages sent to certain addresses to be converted into text messages and delivered to the recipient’s mobile device.

Why are text messages faster than email?

Text messages are generally faster than email messages for several reasons:

  1. Text messages are all very short (160 characters or less with very little “extra metadata” like email headers).  As such, it is very easy for servers to process them.
  2. There is very little text message spam and no text viruses.  As a result, the servers processing text messages do not have to perform a lot of extra work scanning messages.
  3. Good capacity. The big mobile providers ensure that the servers supporting their text messaging services have plenty of capacity to support all of the normal demand — and without spamming and other attacks common to email, this demand is much more uniform and predictable.
  4. Push delivery. Text messages are “pushed” to the recipient’s mobile device so that they are notified of the message as soon as it arrives.  In many cases with email, recipients may not be notified of new messages for one to several minutes after the message actually arrives (depending upon the email system and technology used).

So, then why are they not always delivered right away?

Generally, all of these considerations results in very fast delivery.  However, there are things that can result in delays in message delivery (not to mention lost messages):

  • Poor sender signal. If the sender’s cellular device has a “poor signal”, then text message may be delayed in sending, or not sent at all.
  • Recipient phone off. If the recipient’s phone is off or disconnected from the network, the text message will not be delivered until it is back on and online.  I.e. think of airplane travel…
  • Poor recipient signal. If the recipient’s cellular signal is poor, then the text message might not be able to make it through and it could be delayed until sometime after the signal is better.
  • Message Queued. Just like email, if the text message cannot be delivered to the recipient’s phone, it is queued by the cellular service for later retry.  When it is retried, how often, and for how long, all depend on the cellular service.  So, even if the recipient loses signal only for a few seconds, that could cause a text message to be undeliverable and queued, and not delivered until some unspecified time in the future.
  • Email to SMS Gateway. When using email to send a text message, the message has to travel through some email servers (the sender’s and the SMS email gateway servers of the recipient’s cellular provider) for the first leg of the delivery trip.  The use of email itself can cause some delay, as email is not instantaneous.  Of course, if the sender’s mail servers are very reliable, then this may not be a significant factor.
  • Emergency! In the case of some significant emergency (like a natural disaster), everyone may be using cell phones and texting.  This abnormally large usage puts quite a strain on all cellular service providers and can also result in regular text messages being delayed or not delivered.

So, are text messages good for notifications?

Yes, text messages are a good vehicle for receiving notifications, in general, as long as you have a good signal.  They may be better than email in some cases to differentiate the notices from normal messages, and so that you get alerted right away by the text (without needing to be alerted right away about all of your other email).

LuxSci offers use of text messages for many things such as:

This service uses the “Email-to-SMS Gateway” to deliver these messages.

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