Troubleshooting WhatsApp Phone Verification Issues: OTP Not Received

Symptom

You are attempting to verify your phone number during WhatsApp Business registration via Embedded Sign-up, but you are not receiving the SMS or Voice call containing the verification code (OTP).

Applies To

• Embedded Sign-up

• Messages API

Cause and Resolution

1. Phone Number Requirements Not Met

Ensure your number meets all of the following:

• Supports SMS or Voice calls (preferably both)

• Has international inbound reach (codes are often sent from US +1 numbers)

• Is not currently registered on WhatsApp (personal or business) — it must be fully deleted before onboarding to the API

• Is not a short code or toll-free number

2. Using a Vonage Virtual Number (LVN)

For SMS verification:

• Check your SMS Logs in the Vonage Dashboard

• Set Direction to Inbound and search for messages from international senders around the time you requested the code

• Note: Identity verification messages are not delivered to webhooks — you must check the logs directly

For Voice verification:

• Vonage numbers must have call forwarding configured to receive OTP calls

• Go to Dashboard → Numbers → Edit your number → Voice Settings

• Configure Forward to Phone with a number you can answer

• Refer to: How can I handle inbound calls to my voice-enabled virtual number?

3. Number in WhatsApp Cooldown or Verification Lock

If the number was recently deleted from WhatsApp or has had multiple failed verification attempts, Meta may apply a temporary cooldown.

• Wait at least 10 minutes between retry attempts to avoid triggering a verification lock

• For recently deleted numbers, the cooldown can be up to 24 hours

• If locked, the number may appear restricted in Meta Business Manager

4. International Reach / Carrier Restrictions

Meta sends verification codes from international numbers (typically US-based +1 numbers). Some numbers — particularly in India, Singapore, and other regulated markets — may be affected by:

• International inbound being blocked by the carrier

• DND (Do Not Disturb) registry restrictions

• Carrier spam filtering treats OTP messages/calls as promotional content

• A2P traffic restrictions blocking automated delivery

Solution:

• Contact your mobile carrier to enable international inbound reach

• Ensure the number is not registered under DND restrictions

• Ask your carrier to whitelist A2P/OTP traffic if needed

5. Voice OTP Call Cuts Off Early

"Sometimes we receive calls where only 3 digits are said, and the call is cut."

This is a known behavior. The OTP is a full 6-digit code — the call is being disconnected before playback is complete. Possible causes include:

• Call answered late or dropped mid-playback

• Network jitter or VoIP truncation

• IVR or call forwarding interrupts the audio

• Carrier clipping the automated message

Solution:

• Answer the call immediately when it comes through

• For Vonage LVNs, ensure call forwarding is configured without IVR or intermediate routing

• If the issue persists, switch to SMS verification as the preferred method

6. IVR or Call Routing Interference

If using a contact center number or a forwarded number:

• Automated attendants may prevent the OTP call from being answered correctly

• Chained call forwarding can introduce delays or audio truncation

Solution: Configure direct call forwarding without intermediate IVR, and temporarily bypass automated attendants during verification.

7. Device & Network Issues

• Poor cellular signal may prevent SMS or voice call delivery

• Dual SIM devices may have the wrong SIM active for incoming calls/SMS

• Switching networks or enabling airplane mode during verification can interrupt delivery

Solution:

• Ensure a strong network signal (4G/5G or stable Wi-Fi calling)

• Verify the correct SIM is active for incoming communications on dual SIM devices

• Stay on the same network throughout the entire verification process

Errors: 

“Unable to send verification code, please try again.”

"You’ve tried too many invalid verification codes"

Additional Information

For Vonage LVN issues, contact Vonage API Support with:

• Your API key

• The phone number you're trying to verify

• Whether you selected SMS or Voice

• Date and time of your verification attempts

• Whether you checked SMS logs (SMS) or call forwarding configuration (Voice)

For your own mobile or landline number: The issue may be with Meta's verification system or your carrier. Contact Vonage API Support, and we can escalate to Meta on your behalf.