Frequently Asked Questions

The Frequently Asked Questions section contains the answers to the main questions that CarrierX API users ask.

How can I get access to CarrierX API?

The first step to using the Core API is obtaining a CarrierX account. To do so, please submit a request through our Contact Us page.

Please refer to our Getting Started section for more information on how to start work with CarrierX API.

Is it possible to try CarrierX API not through terminal, but using some other methods?

Rather than use cURL commands in the terminal, you can explore the API using Postman, a stand-alone client with a user-friendly interface. Postman is widely used for API development and allows you to test requests.

Please refer to these API Reference sections for more information on this and links to the Postman collections for available CarrierX API:

How all the sections (Core, Conference, FlexML, and Mediator API) of CarrierX API are interconnected?

CarrierX partners start with the Core API to set up their accounts, rent phone numbers, change the rented phone numbers settings, send text messages, manage the storage, and create endpoints. Once you set up, for example, a Conference endpoint with the Core API, use the Conference API to create conferences and place calls to them.

The same routine is used for the other endpoints: first they are created with the help of the Core API, and then they are managed with the dedicated API (Conference, FlexML, or Mediator). Refer to the Quick API Reference to learn more about the API sections and how they are related to each other.

What are SMS/MMS pass-through fees?

Some mobile carriers apply small surcharges on certain types of message traffic (e.g., SMS or MMS ) when the messages use their networks on their way to the recipient. When applicable, such pass-through fees are charged per message segment for SMS, and per message for MMS. CarrierX passes such fees through to our customers.

Some carriers charge fees on SMS sent both from long code (a 10-digit US number) and short code numbers. Other carriers only charge fees for SMS sent from a short code number.

Currently, the following additional fees apply to outbound messages:

SMS - Local Numbers

Carrier Pass-through Fees
US Cellular $0.0050 per segment
Verizon $0.0025 per segment

SMS - Toll-free Numbers

Carrier Pass-through Fees
Verizon $0.0025 per segment

MMS - Local Numbers

Carrier Pass-through Fees
US Cellular $0.010 per message
Verizon $0.005 per message

Please refer to this page for more information on SMS/MMS costs:

I could not find the answer to my question here. Where else can I ask it?

If you could not find the answer to the question you have here, please feel free to contact our technical support at and our team will get back to you as soon as possible.