I don't know what you were looking for exactly or what you found, but a

SIP Refer

will include all the original

SIP INVITE

information, as far as I'm familiar with the standard and SIP signalling systems, you're not supposed to add information a SIP Refer, as you will be 'tainting' the origina

SIP INVITE

and thus, you can promote identity theft or financial losses. So, potentially, the information you found - was there in the first place.