Twilio cannot understand parts of your SIP URI. This may be due to invalid characters appearing in the user, params, or headers portion. While Twilio may still attempt to complete your call, the parts of the URI that are invalid will be ignored.
The format for a valid SIP URI is defined in RFC 3261.
Possible Causes
The user-portion of the URI contains invalid characters. The user-info portion allows alphanumeric characters, hyphens, underscores, and a small number of additional punctuation characters.
A URI header or parameter value contains punctuation or whitespace that is not escaped.
Possible Solutions
If you specify SIP headers in your URI, ensure any non-alphanumeric characters in the header values are escaped. For example, to add a User-to-User header with value 0A1B2C3D;encoding=hex, you must encode this into the URI as User-to-User=0A1B2C3D%3Bencoding%3Dhex.