asterisk users - Jun 2005 - Dial(SIP/xyz&zap/r1/123) with different Caller Ids ?!

Hi,
I want to let an incoming PSTN call on an PRI span 1 (TE410P)
simultanously ring an SIP-Device and a legacy PBX connected as CPE on span 
3.

eg. via Dial(SIP/BrunoVoigt&Zap/r3/555${EXTEN}).

PSTN CallerId is 01701234567 transformed in incoming context to 
001701234567
because 0 is the lead number for outgoing PSTN calls.

I want to present CallerId 001701234567 to the SIP-Device,
but 01701234567 to the legacy PBX.
(outbound calls from it are directly passed thru to the PSTN PRI trunk).

Currently the legacy OPBX also sees 001701234567 which it internaly 
transforms
it to 0001701234567 for its connected phones.

Is it possible to set the CALLERID somehow differently for each 
simultanously tried call?

Are there other strategies out there to try?

Thanks in advance for any hints,
Bruno