SMS: Understanding Message Segments

This article was developed to describe how message segments work with Short Message Service (SMS) and the Forth CRM.

What is an SMS?

SMS stands for Short Message Service and is the most widely used type of text messaging. With an SMS, you can send a message of up to 160 characters to another device. Longer messages (>160 characters) are normally split up into multiple messages called Message Segments.

How / Why are messages split into segments?

There are two (2) types of message encoding used by carriers: GSM encoding and USC2 encoding. Both split the message into segments based on the number of characters each encoding allows. GSM (most common) contains a maximum of 160 characters per segment while USC2 contains a maximum of 67 characters per segment. The type of phone/device receiving the message determines which encoding is used. 

How does this affect me?

NOTE
The Twilio cost per message segment is $0.04 ($0.0375 per segment plus $0.0025 carrier fee); Forth related costs are not impacted by messaged segmentation)

Cost (Twilio Only) 

The number of segments affects the Twilio cost and the time it takes for your SMS campaign to complete.

Cost example:

4 Segments X 1000 Contacts = 4000 Message Segments Sent

4000 Segments X $0.04 = $160

A single run of this example campaign costs @$160. If you send that SMS Campaign 4 times per month = @$640 a month. Sent daily, this campaign could cost @$4800 a month. 

You could easily send tens of thousands of SMS messages that are split into segments. However, if you review your messaging templates and reduce the length of the message (reducing the total number of characters to be sent), you can reduce the costs of SMS campaigns significantly. 

Time

• NOTE
  Twilio puts a 14,400 segment-limit for local numbers. Forth has built-in checks to catch campaigns reaching queue limits. This functionality delays messages if the limit is reached and runs them once the queue has been cleared. Again, this adds time to your campaign run time. 

The length of segments also affects the time it takes for campaigns to complete. Twilio limits the message rate sent from non-Toll Free Numbers (aka Local Numbers) to one message segment per second.

Example: 

Local Number: 4000 Segments at 1 Segment per Second = 4000 seconds or 1.11 Hours

What should I do?

SMS Campaigns are effectively sending text messages to a set of contacts. These messages should be short as opposed to lengthier and more verbose email messages (by contrast). With an SMS message, find the focus of the message.

Example:

You have an upcoming payment due on {NEXTPAYMENT_DATE} for ${NEXTPAYMENT_AMOUNT}. For any questions, please call (888) 555-5555. Reply STOP to end texts.

This message is a payment reminder, so the most important information is the payment date and amount.  The result is a 1-3 segment SMS depending on the receiving carrier. By reducing the size of the message you’ve now reduced the time it takes to send the message and the cost of sending the message.

What other options do I have to reduce the cost or delivery time of my SMS campaigns?

• Split or divide SMS Campaigns across multiple local numbers (additional local numbers are available from Twilio)
• Avoid overlapping SMS campaigns by staggering the start time of the campaigns across multiple windows per day or week, leaving ample time for a campaign to complete before a new campaign begins.
• Use SMS campaign appropriately. Some messages are better suited for email depending on the content. 

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