Basic Format

In its most basic form, a text sender ID has the following format:

Carrier and handset support for sender IDs in this format is universal, with very few exceptions. Operators in some countries, such as India, have technical support but require pre-registration to comply with marketing laws. Get in touch if you have questions about this.

Blank space

Most operators accept spaces in the sender ID, such as ”The Elks”, but handset compatibilty is hit-and-miss. We've seen that models of iPhone running specfic versions of iOS will remove the space and display ”TheElks” instead of ”The Elks”. This is can change the tone of a message quite a bit — for instance, ”YOUR AGE” vs. ”YOURAGE”.

In other cases we've seen handsets drop the message entirely. That is, the message is received but is never shown to the user and isn't in their message history.

Full stop

Basically the same situation as for blankspace — operator support is good but handset support is hit-or-miss.

Other characters

When we send your SMS to the operator, the sender ID is sent as a 21 octet field encoded as either GSM-7 or Latin-1. There's nothing in the protocol that pervents any character in the GSM 03.38 alphabet (such as åäö or !) from being used in the sender ID. In practice though, most characters outside of the [A-Za-z0-9] range tend to be either filtered by the operators or not supported by the handsets.


It will not be possible for the recipient to reply or call you back when you are sending SMS messages using a text sender ID. This is a limitation of the mobile networks — the choice is either a phone number or a text sender ID.

Some countries and telecom operators does not support Text Sender ID. For example SMS to the USA will not work fully with Text Sender ID. The sender ID is replaced with a random phonenumer if the operator dosen´t support text sender ID. This is done automatically and does´t requre any extra setting on your account.

API support

By default, the 46elks API only accepts text sender IDs that are between 3-11 characters long and limited to the characters [A-Za-z0-9]. Also, it may not start with a number.

We can remove these restrictions from your account upon request, though we can only offer very limited support if you choose to do so. Get in touch with our support and we'll help you out.