---
page_type: error
code: 21601
message: "21601: Phone number is not a valid SMS-capable inbound phone number"
level: ERROR
---

## Error - 21601

### Phone number is not a valid SMS-capable/MMS-capable inbound phone number

The phone number you provided as the FROM field to initiate an outbound message is not an incoming phone number assigned to your account. Only phone numbers that you buy from Twilio can be used for outgoing messages. In particular, 3rd party phone numbers such as validated CallerIDs cannot be used to send messages.