The article shows that on LiveKit you can retrieve the caller's number by accessing sip.phoneNumber from the SIP participant's attributes after connecting and waiting for a participant, unless hidden by a dispatch rule. For Twilio Media Streams, the start message lacks the caller number, so you must forward the {{From}} value as a (name and value under 500 characters) for the voice agent to receive it. Pipecat will only pick up the number when it is supplied via this forwarded parameter.