Unable to send SMS from my Claude MCP connector

Hello,

For the last few weeks I’ve integrated Claude to send out appointment reminder texts in the mornings to people I have booked calls with that day. As of yesterday, it returns an error every time I try and get Claude to send a text. 

 Every send_sms call comes back with:

{"data":{"status":"rejected","retryAllowed":false,"reason":"verification_unavailable"}}

Details:

• Sender: my own direct number, which is SMS enabled. SMS from this number works fine through other routes, including the RingCentral app and a Make scenario, and those messages show as Delivered in my message store.
• Recipient: US mobile numbers in E.164 format.
• Each attempt used a new request UUID. Two attempts on 10/22/2026 around 11:07 UTC, both rejected the same way.
• Other tools on the same connector work normally: call log, call AI notes, and the SMS and voicemail inbox.
• The calls were made from an automated Claude session and from a Claude Artifact page, not from the Claude chat window.

Questions:

1. What does “verification_unavailable” mean for send_sms?
2. Is this a known issue and is there a fix, or is this likely something on my end?

Thanks,

Kent