Im here in the USA california, and I have a n900 and and tmobile sim that I'll mostly keep used in my motorola milestone. Now is there a way to still recieve calls through skype or something else on the n900 without a sim card inserted and without any wifi or internet connection?

skype needs an internet connection of some sort to work

So you can use Wi-Fi.

Just use WiFi, where it is avaiable

Then you can talk into the n900 like normal for phone use?

exactly ... u can call skype to skype

or skype to any phones ( u have to pay for 'to phone calls' but really cheap, i guess )

Here we are talking about several things, and lump together will be very confusing.

There are atleast 3 ways to receive phone call from your N900
a) N900 is a cellphone. Requires a sim card/cellphone number, a cellphone plan, cellphone sat tower connection. No matter how you set your phone, it will receive phone call when the cellphone number is being called provided the above conditions are met, presence of a sim card, in have an active cellphone plan and in connection to your cellphone sat tower. Sure, it will dial out too if the conditions met, but it was NOT asked in OP question.

b) N900 is also a "PC". It can receive and dial out if you installed the right software, online, using as an internet phone (data package), Skype is one of them. No. You do not need a sim card to use Skype. However, to make it work is not easy, there are quite a few of them, and this is the way I did it, using it as a free phone. and it has been working so far for several months. And sure, one can do Skype to Skype call, and you will receive phone call from Skype call ONLY if you are online.

c) using a combination of the above, using your sim card and the phone feature to get online (data package), then use b) above to carry out the receiving/dial out. Yes, it is totally working, depends on your cellphone plan. See, you are using your cellphone to get online then use the internet phone to talk, so you do need a very good cellphone signal/bandwidth, 3G and above should be OK. Using a cheap dataplan to achieve this, you will need a lot of tweaking, http://talk.maemo.org/showthread.php?t=37887 ; Currently I am only successful with 2.5G, it is enough to call using skype to reach people, but it is too slow to carry out a meaningful conversations. Only to receive phonecall using a cheap dataplan, like tmobile's pay as you good, it will cost you $ EVEN if you choose NOT to pick up the phone, apparantly, people can text you SMS, leave voice mail, or whatever, it will count in a premium rate like $.15 per minute. Bottomline, NOT recommended.
You do need your sim card in, for this situation, as you need to get it to get online 1st. And since your simcard is in, when someone called you on your phonenumber, your N900 real phone feature kicks, it will cut you off from your datapackage use, so you will be offline to answer your phone call, when finished, you can have the option to get back online using data package.


I think that is all I know about phone today, anybody wants to chip in more? TIA,

bun

You can also use SIP in conjunction with a WIFI connection. There are several paid and also free SIP services available.

I have been using SIP2SIP for years with little issue. There are several others which have a good running record as well.

Just another option

I pay $30 a year to call any regular phone in the US from my N900 using Skype and my wireless connection. My friends in Moscow use Skype, so I can call them for free.

(Incidental aside: using Vonage, for which I pay $30 a month, I can call Moscow from my Vonage phone to a regular phone for free. I tried it!)

I got a $3/mo plan on Skype on my n900 but am unable to call US phones. I can call them thru my computer but not thru my n900. When I try to call thru my n900 i get an error message saying that Skype requires numbers in international format. ??