Nokia 6100 phone not really suitable.

It's very hard to get an RS232 data cable for this phone that plugs into the bottom.

Most of the cables use a device that houses the battery and sim and fit into the battery cavity.

I have tried this cable and coul not get it to work.

I recommend 6210 or 6310 or 7110.  These all seem to use the same data cable which are available for about £8.