Both Nokia & M55 are not supported by ASP.NET.
i.e. they do not have a profile in the machine.config file[s].
If you want to work with these devices you need to create the profile
yourself,
and add it to the <browserCaps> secation, either in the machine.config file
or in the web.config file of your application.
You will have to read the documention to find out exactly which settings are
appropriate for these devices.
try looking at http://www.asp.net/mobile/profile/default.aspx.
This web site helps you check your mobile device and find out which settings
are appropriate for it.
I've added profiles for several devices (Telit,Nokia6360,samsung
SGHX450,Telit)
But it trial and error(basically you create the proifle and then play around
with the settings and see how it looks on the device).
And now I'm trying to add a profile for Nokia3100.
I've managed to create a profile that works with wml12, but does not display
color.
the Nokia3100 supports xhtml, but I could not get it to work with ASP.NET
(I get "invalid length for Base-64 char array" error when clicking on a link).

A pity Microsoft stopped issuing Device Updates (the last one was on
12/2003!).
Hope this helps,
Nadav