On an outgoing IP-PSTN call is it possible to modify a SIP Contact Header record so that the displayed CLI is associated with a trunk group?

E.g. sip:xxxxxxxx;tgrp=yyyyyyyy;trunk-context=domain.com@100.100.100.100:5060;transport= UDP>

where xxxxxxxx is the CLI we want to display
where yyyyyyyy is the originating trunk group the CLI is assoicated with.

We want to make outbound calls via a Broadsoft platform and display a different CLI from the main trunk identity. Our ITSP will allow this if we can send a SIP contact header formatted as above. (Format defined in RFC 4904 apparently)