Reason 1 - Sending long SMS

An SMS comprises segments and each segment is 160 characters long. So if you are sending a lengthy SMS, it will consume multiple segments and thereby drive up your cost. 

Please note that while 160 characters form a segment, even using 161 characters counts as 2 segments.

Character lengths of segments also vary by countries & regions which might be another reason for your high SMS cost.

Reason 2 - Having hidden characters in your SMS text

Many agencies copy/paste the SMS text body while designing automation. When you copy/paste text from a text editor software like MS Word or Google Docs, sometimes hidden characters get appended in the string. These hidden characters can not be seen by the user but they are present in the text. 

Example

In this example a simple phrase Hey there was copied from a webpage. Usually, it should be just 1 segment. But actually, it contains many hidden characters (empty characters) making this as large as 4 segments. 

You can use https://twiliodeved.github.io/message-segment-calculator/ to check the actual number of segments & character length of your SMS text.

While pasting contents of an SMS to System text editor it is recommended to use paste as plain text option instead of simple paste

Reason 3 - Using Emojis

This is the most common reason for unexpected high costs while sending SMS automation. 

Example

In the example below some emojis were used that increased the number of segments from 1 to 4.

Using emojis is a great way to make your automation exciting but being aware of the costs involved will help you make an informed decision about their frequency of usage.

Reason 4 - Using a picture attachment

Both SMS and MMS carrier fees will apply which could drive up the cost of each SMS. When you send a picture message with text, you get charged $0.02 for the picture + the usual SMS cost depending upon the length of the text.

For example,

 If the following text portion of the Picture SMS is 2 segments - 

"Hey Shivam, this is Kate from BusinessName, just wanted to let you know that this upcoming Monday, we have a new update for your agency, REGISTER HERE: bit.ly/BIZ-xxxxxxxx or text MOREINFO for more info!"

We will charge $0.0075 x 2 = $0.015 for the text portion.

If there's an image attached to this message, it will charge at $0.02 / message

So the total cost per message is $0.02 + $0.015 = $0.035

Reason 5 - Carrier fees

Further, there might be some additional charges incurred:

• MMS-MESSAGES-CARRIERFEES

• PHONENUMBERS

• SMS-MESSAGES-CARRIERFEES

https://www.twilio.com/sms/pricing/us