Twilio Docs

SMS
Voice
Runtime
Video
Studio
All docs...

SDKs
Help
Log in
Sign up

SMS
Voice
Runtime
Video
Studio
All docs...
SDKs
Help
Log in
Sign up

Twilio

Menu

Error Reference

Collapse Expand

Rate this page:

Error 21604

Error - 21604

'To' phone number is required to send a Message

Make sure to specify a valid phone number as the recipient of the message.

Rate this page:

Terms of Service
Privacy Policy
Copyright © 2021 Twilio Inc.

Thank you for your feedback!

We are always striving to improve our documentation quality, and your feedback is valuable to us. How could this documentation serve you better?

If applicable fill in the countries where you are using Twilio

Talk to Support

Protected by reCAPTCHA – Privacy - Terms

Sending your feedback...

🎉 Thank you for your feedback!

Something went wrong. Please try again.

Thanks for your feedback!

Refer us and get $10 in 3 simple steps!

Step 1

Get link

Get a free personal referral link here

Step 2

Give $10

Your user signs up and upgrade using link

Step 3

Get $10

1,250 free SMSes
OR 1,000 free voice mins
OR 12,000 chats
OR more

Learn more about the referral program