The Envelope App does not send SMS messages itself. Instead, it passes the message request from the TaxiCaller system to the SMS application on your device — the same app you normally use to send and receive text messages.
Messages failing to send
If messages fail to send, the most common cause is a configuration issue in the system.
For example, the user account may be configured as a Driver or Dispatcher, but not as a Messenger. In this case, the system will not allow SMS notifications to be sent through the Envelope App.
Make sure the user sending the message has the correct Messenger permissions configured in the system.
Messages marked as sent but not received
In some situations, the message may appear as Sent, but the passenger does not receive it.
When the Envelope App shows a message as Sent, it means that the app has successfully passed the SMS to your device’s SMS application, and the SMS app has confirmed that it attempted to send the message through your mobile network.
You can verify this by checking your SMS app, where the message should appear in the sent messages list.
If the message appears there but the recipient did not receive it, the issue is usually related to mobile network delivery rules rather than the Envelope App itself.
Common reasons why SMS messages may not be delivered
Mobile network providers apply various filtering and delivery rules to SMS messages. Some common reasons messages may not reach the recipient include:
Spam filtering by the sender or recipient network
Mobile carriers may block messages they believe are spam, especially if the message is sent repeatedly or contains promotional or automated-looking content.
Messages containing links or redirect URLs
Some carriers filter or block SMS messages that contain shortened links, redirects, or unfamiliar URLs.
A2P (Application-to-Person) messaging restrictions
Some networks treat automated messages differently from regular person-to-person messages. If a message appears to be generated by a system, the carrier may restrict or filter it.
Special characters or emojis
Certain characters or emojis can change the encoding of the SMS message or trigger spam filters, which may cause the message to be blocked or rejected by the network.
Carrier or regional restrictions
Some countries or mobile operators apply stricter rules on SMS delivery, especially for automated or business-related messages.
What to do if messages are not delivered
If the message appears in your SMS app’s sent messages, the Envelope App has completed its role in sending the message.
In these cases, we recommend contacting your mobile network provider, who can check whether the message was blocked or filtered during delivery.
If you continue to experience issues, our support team can also help review your configuration to make sure everything is set up correctly.