Interrupt Playtones application

Hi all…
I want to setup my asterisk in order to achieve this:

I get the phone, press 0# and get a new dialtone! This tone will indicate a external line, like in a normal PBX.
When I press the first digit of the extension I want to call, the Playtones is interrupted. Searching for this in the web, I fount one talking about a patch to the playtones extension that will accept the i parameter, like this:

Playtones(dial|i)

this will interrupt after the first digit is pressed. The reference link is:
lists.digium.com/pipermail/aster … 16480.html
but this link is broken!!
anyone have done something similar to this?

regards
Carlos Barros