Anyone know how to disable LAPM on the Nokia 6310i?

Hi all,

I am trying to connect to a Nokia 6310i using a modem which doesn't
support LAPM. I am successful in Australia, but when I try it in some
locations in the US, I cannot get a connection.

The modem manufacturer's tech support tell me that the Nokia 6310i is
requesting LAPM. Usually, if one side does not support LAPM, then the
other side will eventually give up on LAPM connect without it.
However, this is not happening and the Nokia 6310i eventually gives
up.

Anyone know how to disable LAPM on the Nokia 6310i?
I've tried the at+es=?, but I just get "ERROR".

Thanks,
Patrick