An SMS Sender ID or SMS Customer ID (or simply put sender name) is the displayed value of who sent the message on your handset with a registered mobile number. For example, the Sender ID of your friend is their phone number. It can also be a shortcode, such as 12302. Or contain a limited number of characters, e.g. CoffeeShop.

Picture showing what is an SMS Sender ID

The different types of Sender IDs are usually the first points touched upon when starting to use the service.

Long numbers are the numerical sender IDs, which are the same length as the national mobile numbers (up to 15 digits long, not including the + symbol). For example, 3725953854.

Shortcodes are special numerical senders that are shorter than the regular numeric senders that are used as phone numbers. These types of senders may have different uses depending on the region the messages are being sent. Generally, in Europe, such numbers are used for services like customer support, voting, premium rate services, etc. Whereas in Latin America, shortcodes are the most typical types of SMS Sender IDs. For example, 12302.

SMS API Integration Checklist

Alphanumeric Sender IDs are sender names that are composed of letters from the alphabet (A-Z), and numeric characters. This sender represents the brand name and is displayed as such when you receive a message (e.g. new text message received from Messente). This is for single-way communication with your customers.

It is important to note, however, that not all countries and operators offer all these Sender IDs for use even if the SMS service provider supports them. It really depends on the limitations set by different countries on Customer IDs finding usage in customer interactions, mobile banking, and other integrations.

SMS Sender ID verification

Whether it is an alphanumeric sender or a shortcode, the Sender ID or Customer ID verification process is used despite what kind of Sender ID you are applying for.

Here in Messente, for example, we take various steps to verify SMS sender IDs for different phone numbers. The goal is to make sure that the Sender IDs are being used lawfully and so that no-one could misuse them.

Another reason for this process is the ever-changing operator and country regulations which affect the registered phone and mobile numbers.

A simple registration is relatively easy and after the verification, all should be set. But unfortunately, that is not the case everywhere. The sender registration process in the background is more complicated than that.

Some countries have a very complex registration process in place to send your messages to their subscribers, whereas some operators do not allow alphanumeric Sender IDs at all, so it can become a real hassle to make use of Customer IDs in cases like this.

Two-way messaging with Sender IDs

The nature of the SMS Sender ID brings about various possibilities in terms of appearance and use cases, one of which is two-way messaging. Although, the availability of such a feature depends whether the Sender ID is a numerical one or an alpha sender.

For two-way messaging to work, a numerical number is needed. In order to enable two-way messaging, a number needs to be registered by the partner beforehand. You have two options to choose from:

  • Long Number Sender ID - as covered before, it will appear on the recipient's handset as a long number (e.g. a mobile number). This enables two-way messaging for that number. The sender can reply directly back from their mobile number, and the reply is forwarded over the API or e-mail.

    Picture showing an example of a long number sender ID
    An example of a Long Number Sender ID
  • A Shortcode Sender ID – this Sender ID is like the previous long-code option, only that there is a little more variety in the short-code types:

   o Dedicated Shortcode – this is a little more expensive version. A single company is the owner of the specific shortcode. This is almost always covered with two-way messaging, with no keywords required for the communication.

   o Shared Shortcode – multiple entities share these shortcodes, meaning that several companies use the same Sender ID to notify their customers. In these cases, two-way communication is also possible when using a keyword to send an sms (for example: “Reply with MESSENTE if you wish to know more”).

Examples of dedicated shortcode SMS sender IDs

SMS restrictions on Sender IDs

Due to the global nature, there are a variety of different measures taken by the mobile network operators to regulate the messaging on phone numbers.

A lot of the operators have incorporated their own business processes, restrictions and regulations in every aspect of the text message from the Sender ID and content restrictions to the process of how messages can be submitted to their networks.

As the variety and the number of different regulations is quite high, we will outline a few of the more common ones:

  • Registered sender names only – In some countries there is a specific restriction, where A2P messaging is allowed only when they are whitelisted (registered) with the network operators.

This is set in place so that either the operator itself or the central government agency in the destination country would have a simple way of tracking the message back to the original sender.

  • Sender ID restrictions – Many mobile network operators restrict the sender name types. The reasons for this vary, depending on the types of Sender IDs allowed.

Some mobile operator networks allow only active long numbers for the recipient to have a clear and simple way to contact the sender.

On the other hand, some operators only allow Alpha Sender IDs to be passed through the relevant channel to ensure that the recipients would clearly identify the brand trying to contact them.

Lastly, a few countries have set in place a set of regulations so that only shortcode senders would be allowed through, which are licensed directly from the operators.

  • Sender signature included in the text – In some countries, the sender info must be included in the message body itself so that the customer knows this is a correct message.

Another reason for it can be due to country regulations where this signature serves as a verification of the official sender who uses a long number Sender ID.

  • Spam filters – Almost every mobile network operator in the world requires that their clients and messaging partners prove strong spam prevention mechanisms. This is used to stop repeated messages being sent, or technical problems that could cause such issues on phone numbers.

Also, messaging content is closely observed to stop any scam messages, inappropriate messages and messages that are against the local regulations set for restrictions via sms.  

SMS API Integration Checklist


When choosing your Sender ID, make sure that you consider the goals and needs of your business. Do you need two-way messaging? Go for Long Number Sender ID or a shortcode. If not, alphanumeric one.

Also, make sure that you follow all the regulations. Different countries have different rules and regulations. Some of the Sender IDs might not work in a specific country. An SMS API service provider can help you with all of this.