DialOut based on SIP_HEADER information

I’d like to process a SIP header packet information got from a provider when I try to make an out call.
I put the string NoOp(${SIP_HEADER(From)}) just after the string with a DIAL command (in the [macro-dialout-trunk] placed within extensions_override_freepbx.conf) but it displays only an extension related information, not VSP peer. What’s wrong? I want an VSP related information seen in the SIP_HEADER var. Thank you.