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How do I create a SIM webhook?

1

Find the SIM

First find the SIM’s details page from the SIMs pages or using global search.
2

Open the Webhooks tab

Open the Webhook tab for the SIM, and in the Configure inbound webhook card, click the Generate webhook button.
Generate a webhook card
3

Configure the webhook

In the card that appears, enter the port number that will receive messages, and the protocol (TCP or UDP).
After your webhook is created, you can find the generated URL and port to use listed in the Configure inbound webhook card. Generated webhook card

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Where do I find the SIM’s webhook key?

Your Hologram webhook key is a device-specific identifier used to authenticate your SIM. This key is included in the JSON message body when sending messages to the webhook.
1

Open the Webhooks tab

From the SIM’s details page, open the Webhook tab and click the Show key button in the Webhook key card.
Webhooks tab showing the Show key button in the Webhook key card
2

View and manage the key

A modal will appear that displays your webhook key. You can copy the key or generate a new one. Webhook keys do not expire.
Modal displaying the webhook key with options to copy or generate a new key

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How do I send a message to a SIM’s webhook?

After generating a webhook and getting your device’s webhook key, use the following HTTP request to send a message to your SIM. The body is a JSON object with the following fields:
  • k or devicekey — The device’s webhook key
  • d or data — The message data
  • t or tags - The custom tag name
The custom tag name is optional and can be used to add custom tags (topics) to the event.

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HTTP Request

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Request Body

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How to configure webhooks using the REST API

REST API endpoints

Configure device webhooks GET/POST/PUT/DELETE /devices//webhook

Send messages to SIMs

Send TCP, UDP, or SMS messages to your devices

Troubleshooting webhooks

Fix common webhook configuration issues
Limited access: Only Owners, Admins, and Managers can see the Webhook tab and configure webhooks. Editors can see whether a SIM has a webhook on the SIM details tab.