The Sumsub protocol connects VASPs in the Sumsub Travel Rule ecosystem directly, without an external network between them. The system selects the protocol automatically when the counterparty is part of the ecosystem, so you do not need to configure encryption keys, credentials, or partner onboarding for the protocol. For more information on protocol selection, refer to this article.

How Sumsub protocol works

The Sumsub protocol keeps the exchange within Sumsub infrastructure and synchronizes the transaction state between both VASPs.

When you create a Travel Rule request, a mirrored transaction appears on the counterparty's account. The counterparty can answer it manually or automatically, and later changes — such as adding the blockchain transaction ID, cancelling the exchange, or reaching expiration — are synchronized on both sides.

Sumsub protocol capabilities

The Sumsub protocol combines network routing, request handling, testing tools, data matching, and data protection within the same Travel Rule workflow.

VASP network

The protocol connects you directly to VASPs in the Sumsub Travel Rule ecosystem and routes requests to the relevant participant.

• The ecosystem includes 600+ active VASPs. For the list of participating VASPs, see this article​.
• You can invite a counterparty outside the ecosystem by email. The counterparty can join with a free Sumsub account and answer the request using the same protocol.
• Requests sent to a VASP group are routed to the entities within that group. The entity that confirms wallet ownership becomes the counterparty for the exchange.

Answering requests and communication

Counterparties can answer requests asynchronously and communicate directly with the other VASP when additional information is required.

• After a request arrives, the counterparty reviews it and confirms the wallet.
• The counterparty then attaches the relevant user within the configured timeout.
• Employees of both VASPs can message each other and request or share documents on the exchange using Travel Rule messages.

Testing and integration

You can inspect the complete flow in the Dashboard and test the integration before using it in production.

• In the Dashboard, you can create a request, answer one, and observe status changes.
• Use Sandbox to test against a VASP that answers as a real counterparty would.
• The Sumsub protocol does not require separate protocol-level encryption or decryption logic because the exchange uses plain Sumsub transactions.
• If you configure the Wallet Address Book and payment methods, incoming requests can be answered automatically.

Data matching and data protection

Sumsub matches exchanged data on both sides and limits what participant data is exposed throughout the exchange.

• Sumsub matches the exchanged data using configurable name-matching strictness. The initiator can see which fields did not match instead of receiving only a generic decline. You can configure these fields in Travel Rule settings.
• PII remains masked until the counterparty confirms wallet ownership.
• Only the fields configured in Travel Rule settings are shared.
• Outcomes are granular — for example, unconfirmed ownership or mismatched data — rather than a single decline status. To see the full list of Travel Rule statuses, refer to this article.

Travel Rule messages

Travel Rule messages allow your compliance team to communicate with the counterparty VASP about a specific transfer. You can request additional information, attach supporting documents, or record details agreed with the counterparty.

Messages remain linked to the transaction, keeping the conversation and its context in one place.

Travel Rule messages are separate from transaction notes. Notes work for Travel Rule transactions in the same way as for other transactions. For more information, refer to this article.

What counterparty sees

The counterparty receives the message text and any attachments on their side of the transfer.

Messages are sent on behalf of your VASP. The counterparty sees your VASP name and does not receive the names of individual employees.

The same applies to incoming messages: they are attributed to the counterparty VASP rather than to a specific user.

Send and read messages

To send a message:

1. In the Dashboard, go to Transactions and Travel Rule → Transactions and open the required transfer.
2. Open the Messages section and click Send message.
3. Enter your message and send it to the counterparty.

Attachments

You can attach files to Travel Rule messages.

The counterparty receives attachments together with the message text. Attachments received from the counterparty are also available in the Dashboard.

Notifications

The system sends notifications only for incoming messages. Messages from users at your VASP do not trigger notifications.

When you enable Travel Rule for your account, the system automatically enables message notifications for all users.

Each user can manage their notification preferences in the Dashboard:

1. Navigate to Profile settings → Notifications.
2. Select the New note added to a transaction by the counterparty VASP notification type and switch the toggle to turn it on.

Users can enable or disable email and Dashboard notifications independently.