PPTP WITH ISA

HI Experts,
                I'm trying to establish a pptp connection from outside to my
ISA server,My scenario is simple, I'm using CISCO 857 and after this ISA
server and I enable pptp on ISA I did'nt configure any pptp configuration on
CISCO 857,So when I try to establish my VPN connection from inside ( same
LAN ) I can its work fine but from outside I can't Its show username &
password prompt n when I put its not work,So my Q is there any config for
pptp needed on CISCO 857 if yes then what it is .And If there is no config
needed so where is problem.

Thanks,
Regards,

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Received on Sat Apr 11 2009 - 14:23:15 ART