Yes,

This is possible...

The document below shows you how to do this..

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00805b6f33.shtml

There are about 4 steps to ge this done..

1. Create a CSS called something like Tranlsation_CSS

2. Create a partition called Translate_PT, assing this partiton to the Translate_CSS. Make sure its only thispartiton that is in the CSS.

3. On your Voice gateway, Go to your inboud calls, and change the css to the Translate_CSS

4.create a translation pattern for all your incoming DID calls...Eg if your Full DDI is 02079011226, then if you are using 4 digit, your Xlation pattern will be somelike 12XX or 1XXX, assign this xlation pattern to the CSS you sue internally on your phones.

On the Calling party xformation mask, you can either use prefix outgoing digits [91] or use calling party transformation masx 91XXX....(the numbr f digits you want)

The prefix outgoing digit is easier, so use that..

makesure you check the use calling party's external phone number mask..

You should be good to go..with this