Thanks David for your response. I had the same understanding but wanted to clarify. I believe the difference lies in configuring translation pattern in CUCM. For SCCP dialer it can be done in CUCM, but I am not sure if it can be taken care of in any other application other than gateway in case of SIP dialer.
I actually happen to be testing this out right now and it doens't work as documented or as we've seen in work with SCCP.
Rather than prefixing the digits onto the dialed number, the SIP message arrives at the gateway with with Remote-Party-ID set to the Campaign Prefix Digits. So it becomes the ANI on the outbound call.
This isn't necessarily a bad way of doing it, but it's rather annoying that it doesn't match the docs.
I don't remember the docs exactly, but I thought for the SIP section of the install/config guide it worked just as advertised and it's so much easier than SCCP.
It is as easy as avertised !
The sip dialer actually ready the campaign prefix digits and uses those digits at the Calling Line ID of the call it places. In the SCCP Dialler we used that field to populate a 2-digit ID which then matched a CUCM route Patteren and modified the Calling Number. This is not required with SIP Dialer because the SIP Dialer does not engage CUCM untill it dilevers the call to an agent.