Texting best practices and guidelines
Carrier restrictions
SMS carriers such as Verizon, AT&T, T-Mobile, etc. sometimes prevent messages from reaching recipients if:
The same DID (phone number) is being used to send messages across their network
The message content is similar or the same
Links or email addresses are included in the content
The total file size is around or over 1.5MB
Some of these restrictions can be reduced or removed, such as link and email usage, similar content, and DID usage, depending on your campaign registration.
Short codes
For clients who want more control over what they can send, including issues mentioned in the Carrier restrictions section, we might recommend using a short code for sending text messages. Short codes are also recommended for sending a high volume of texts.
Note
While short codes may solve these issues, they are much more expensive than long codes, the equivalent of a mobile number.
Learn more about Esendex's short codes.
Message limits
Esendex recommends sending no more than 250 messages per day per DID to help prevent messages from being flagged by mobile carriers as spam due to similar content being sent across one DID.
Opt-out keywords
Texting recipients can reply with an opt-out keyword (STOP, END, CANCEL, UNSUBSCRIBE, QUIT) to stop receiving texts from the phone number that sent the message. It is recommended to stop sending messages to numbers that have opted out.
Note
Make sure not to phrase any expected responses to your questions in a way that could cause recipients to send an opt-out keyword accidentally. Other keywords, like HELP, can also change the Unique Message ID for the sender, so avoid using those words as well.
If a recipient sends an opt-out keyword, they can opt back in to receiving texts by replying RESUME.