My contacts cannot send SMS messages to the short code

My contacts cannot send SMS messages to the short code

When interacting with your target audience via mobile communications through surveys and quizzes, notice or inbox conversations: ultimately the goal is for an SMS message to get delivered, and for contacts to respond to the SMS message in order to have smooth two conversations via SMS.

Sometimes once these SMS messages are successfully delivered to the contact’s phone, they are unable to send in their response back a message to the short code eg to 20788. 
Want to learn more about SMS Messages and Delivery reports? Once a message is sent out, the Mobile networks that handle the delivery of an SMS message and report back on how the message went through what is called a message delivery report. Read our detailed article on how this works on the Echo platform and the different types of delivery status you can see on your SMS messages

This could be a result of various reasons, which are:

Dual SIMs

The contact has a phone with Dual SIM capabilities. This is more commonly found in Android phones which allow contacts to have two SIM cards which ultimately results in them having two phone numbers on one phone.
Messages from contacts may not be coming through because the SMS message sent from the platform through the short code was received with one phone number and the contact is responding to message with the other phone number.


  1. Ask the contact to confirm which phone number they are using to reply to the SMS message that came from the Echo platform and confirm if this is the phone number on the contact’s profile.

Contacts do not know how to respond to SMS

Even with text messaging or SMS being a common form of mobile communication, some contacts may not be aware of how to interact with SMS short codes. Contacts or mobile subscribers may not be aware of how and when they should respond to an SMS from 5 digits short code. 
Contacts may also be apprehensive to respond to SMS messages because they fear that they will be charged for the SMS and it will deplete their credit.


  1. Advocate education for interactions with SMS: If this is your first time interacting with your contacts, sensitize them on what they should expect. If you are planning to send out a survey, let them know that a survey is coming, a day or so before you send. A little anticipation can be effective. Here you can use a 1-way message that comes from the name of your company or project.
  2. Reassure your contacts on the charges they should expect:  If you are working with a Toll-free SMS Short-code, you can reiterate to your customers in the first messages that go out to them that all messaging is free. If you have in-person enrollment process for your SMS engagements, this reassurance of SMS charges can be more in-person or have a personal touch from employees within your organization or by members of your team.

Premium SMS Access

Premium SMS refers to the kind of SMS that you send off using a unique short-code where charges incurred are billed to your mobile credits.  Based on the premium SMS access setting on a contact's phone, a contact may not be able reply to any SMS messages from your short code. This is is because sometimes contact choose to block or to not enable interactions with SMS short codes on their own mobile devices and this blocking normally applies to short codes (such as 20788).  This setting is also known as Blocked Premium SMS.  

This is a unique setting in Android smartphones where once this setting is not enabled on the device, the contact from that point on cannot reply to or send any SMS messages from the short code and will affect all incoming messages or messages that will be sent from the contact's phone.

Want to learn more about opt-out blocked contacts and learn more about how contact opt-out or block SMS from a short code? Read our detailed article on blocked/opt-out respondents, who they are and how you can retain them.


For these contacts to be able to respond to your messages, the contact must enable the premium SMS feature on their phones.  Here's a short video on how  you can allow premium access on an Android phone. Searching Google for "how to unblock premium SMS permissions on X brand" should give you more options on how to find this setting within various phone brands.