21837: Port Order: Phone number is already in the porting process

The porting phone number is part of a Letter of Authorization that has already been signed.

• The same phone number is already being ported from another port order request
• A port order for this phone number is currently in progress with the current provider
• Multiple overlapping port requests were submitted

• Check if there's an existing port order for this number that's still in progress
• If a previous port order exists, let it complete or have it cancelled before submitting a new one
• Submit the new port order after the existing one has fully completed
• Contact Twilio Support if you believe this error occurred in error