16023: Conference: Participant label invalid (max 128 chars, not CallSid, no '/')

This error occurs when the participantLabel used to add a caller to a conference is invalid. For 16023, the label cannot be longer than 128 characters, cannot look like a Call SID, and cannot contain /, including %2F. You can use participantLabel later to reference a participant through conference participant operations.

• The participantLabel value is longer than 128 characters.
• The participantLabel matches the Call SID pattern, which starts with CA and is followed by 32 lowercase hexadecimal characters.
• The participantLabel contains /.
• The participantLabel contains %2F, which decodes to /.

• Keep participantLabel at 128 characters or fewer.
• Use an application-defined label that does not look like a Call SID.
• Remove / and encoded slash values such as %2F before you send the label in TwiML or in a request that creates a conference participant.
• Store a stable label that your application controls, such as an internal user identifier or descriptive name, if you plan to fetch or update the participant later.

• TwiML Voice: <Conference>
• Voice Conference
• How to Share Information Between Your Applications