Additions and changes to the Twilio platform
When Twilio receives termination traffic from your communications infrastructure to the PSTN, your SIP message can sometimes include SIP Diversion headers if the call was previously forwarded. Twilio will forward SIP Diversion headers it receives to the carriers.
To combat any malicious addition of Diversion headers, Twilio will now check all Diversion headers it receives that contain the Twilio domain. Twilio will verify that the phone number included in the header matches one associated with your Twilio account (either a Twilio number owned by the account or a verified Caller ID). If the header fails this check, Twilio will remove the header.
See the docs for more information.