Custom fields allows you to store additional subscriber information with a mobile phone number. You can then use these custom fields to collect subscriber information during the opt-in process, use them as merge tags in mass messages, and even use them to segment messages to certain subscribers.
To create a custom field got to the List then select Settings > Custom Fields. When you are ready to create a custom field click on the New Custom Field button. Fill out all the information needed:
Label - This will be the name of the customer field.
Type - This is the type of field you would like the custom field to be.
Merge Tag - This is what you want the merge tag to be in messages.
Regular Expression - This is a mechanism for pattern-matching, for example: you can create a regular expression to make sure it is a valid email, a birthdate or so.
Fallback - If you use this field in a merge tag what do you want to replace the field with if the subscriber custom field is blank.
Max Characters - For when a merge tag is used what do you want the max characters to be in a message. This number will be the amount if characters counted when creating the message with the merge field.
For more information on custom fields, see the video below.
In the video, we use the regular expression: \A(happy|sad)\z, which accepts both the words "happy" and "sad" and rejects everything else. The regular expression, whether it is accepted or denied, is not case sensitive. So for this example, Tatango will accept happy, Happy, HAPPY, etc.
To test regular expression, you can use http://www.rubular.com/. When testing, be sure to put a "i" after "/", as this will make your test not case sensitive, which is how Tatango works.