I was wondering ,there is this contact that I have when I was about to chat with her ,I ame to click on her name this yellow notice written in black appeared and said (mobile/online). My question what does (mobile/online) mean ? using a mobile to chat ?if so if I chat with them like this would it charge them money to talk when I send them

There's two ways of getting online from a mobile:
1: at http://mobile.live.com/wlm
2: or installing a program into your phone
if you go through the first option you'll appear as mobile/online and wont be any charge for chatting
for the other option i really dunno
since i haven got a mobile with that

can u chat by voice like or is it only text messages.

another question ,this contact comes online normal 99 % of time  but sometimes  (mobile/online ) written next to the display name ,so is it a cell phone

I live in Australia and i'm with 3 and on my phone you can download MSN (yes MSN, not WLM, they are a bit delayed) and when you sign in, on a computer it usually says in the toast "blah blah has signed in from a mobile device" and on the contact list it says (mobile / online) and its free to send your messages from MSN, but to get MSN on the phone it costs.

well ,if the contact replies will she be charged for sending a messages to me ,and can she voice chat??

I don't know about elsewhere, but in the UK we can use a WAP site such as eBuddy (or indeed the MSN WAP site). (on my phone) It's text based and you basically talk by sending "text messages".

However, I know WLM has told me before that to send messages to a mobile device would cost money (I think this was in the BETA though)

I used the Mobile Chat for over a week when I was working away and the only charges I got was for using WAP (I had free WAP anyway )