Two-Factor Authentication

Overview

Two-Factor Authentication (2FA) is a security feature offered to protect accounts and transactions. Crassula provides 2FA support for various actions and settings, ensuring the safety of financial activities.

See the following table for a breakdown of the actions and settings within Crassula that support 2FA.

2FA related section	Process/Action
Transfer	Internal
	UK local
	SEPA
	International
	Bank transfers
	Bank transfers (local)
	Crypto
	Batch payments
	Drafts
Settings -> Profile	Add phone number
	Delete phone number
	Add Email
	Delete Email
Settings -> Security	Setup 2FA (Text message)
	Change 2FA (Text message)
	Set default (Text message)
	Turn off 2FA (Text message)
	Setup 2FA (Authenticator app)
	Change 2FA (Authenticator app)
	Set default (Authenticator app)
	Turn off 2FA (Authenticator app)
	Change password
Cards	Show pin code

Troubleshooting OTP delivery issues

Before investigating OTP delivery issues, verify the following:

The phone number is entered in the correct E.164 format, including the country code.
You have a stable network connection and can receive SMS messages, calls, or push notifications.

Additionally, verify the delivery status:

Confirm that the OTP message or call was sent.
Confirm that the messaging provider returned a successful delivery status, such as DELIVERED.

If the delivery status indicates successful delivery but users did not receive the OTP, follow the troubleshooting recommendations below.

OTP marked as delivered but not received

If delivery logs indicate that the OTP was successfully delivered, perform the following actions:

Restart the device

Turn the phone off and on again
Request a new OTP after restarting the device

Reinsert the SIM card

Remove and reinsert the SIM card
Wait for the device to reconnect to the mobile network
Request a new OTP

Check device settings

Ensure SMS messaging is enabled
Verify that Do not disturb mode is disabled
Confirm that the device has sufficient available storage
Check whether any third-party applications or spam filters may be blocking incoming messages

Contact the mobile operator

Ask them to verify:

Whether international or service-related SMS messages are being blocked
Whether anti-spam filtering may be preventing OTP delivery
Whether any restrictions exist for messages received from the sender number

Request a new OTP

Wait 1–2 minutes before requesting another OTP
After multiple unsuccessful attempts, wait 10–15 minutes before trying again to avoid potential carrier-side anti-spam restrictions

OTP previously worked but has stopped arriving

If OTP messages were received successfully in the past but have recently stopped arriving:

Follow all troubleshooting steps described above
Inform users that mobile operators may temporarily restrict repetitive or automated messages due to anti-spam policies
Ask users to contact their mobile operator and verify whether OTP messages or the sender are being blocked
If necessary, ask the operator to add the sender to the list of trusted senders.

Country-specific OTP availability

OTP delivery availability may vary depending on local regulations, communication providers, and mobile operators.

In some cases, delivery restrictions may originate from external providers rather than from Crassula:

Certain countries may be subject to external technical or regulatory restrictions affecting OTP delivery.
Confirm that coverage and delivery reliability are continuously reviewed with messaging providers.

Invalid verification code

If users receive an OTP but also receive a "Verification code is invalid" error when entering it:

Verify that the code received by the user matches the code sent by the messaging provider.
If the codes do not match, escalate the issue to the messaging provider for investigation with its local delivery partners.