ZyXel Prestige 1100 outgoing authentication

Hi all,

I have a ZyXel Prestige 1100 which I am trying to configure to work
with our new leased line.

It seems to be almost working, but it seems to want to authenticate
all outgoing and incoming data with CHAP or PAP.

Out ISP doesn't support this and we just need everything to go through
it without any authentication.

Is there any way of turning this authentication off? The only options
I can find are CHAP/PAP, PAP or CHAP - nothing for no authentication.

Or am I just going to have to purchase a new router that has this
option?

Thanks,

Gary.