If you guys can do all of this with the N810, do you guys think you could direct me to some hardware compatible with my N900 to replace the cell chip with a true quadband that supports WCDMA on the 850/ 1900 bands for AT&T 3G?
Thanks,
Kham

no.
I use quad band module as it is

thanks for your posts, blue_led!
looking good
keep us updated.

This is amazing. You are going to have to let us know how it all pans out. I think I might have to replicate this whole process.

Cool! Doesn't microsd card prevents inserting battery?

Isn't your gsm module yet connected to CPU? Actually, i don't thing that using n810 as phone will be useful, but GPRS/EDGE costs the efforts for sure.

Very impressive blue_led, I was wondering if anyone was ever going to try something like this. I'll be following this thread.

First, amazing work being done here. Congrats!!
Is this hack possible on N800? Can N800 be used as a phone too?

@all thank you for appreciations !
@vkv.raju I don't know . i never see an N800.

No.
SD card is not full inserted.I let it out for photo session.

Connections with CPU ? Well ...I will use debug serial port and telit module will be driven by standard AT commands.
A GUI will be come.

Sending and receiving sms from n810 ... priceless.

Hmm... R&D flags description page says that enabling serial port will cause shorted battery life: http://wiki.maemo.org/R&D_mode
Plus powering telit itself... Isn't it going to considerably decrease battery life?

this is a really cool project; at one point i looked into buying an n810w to replace the wimax module with a-3g one as I though it'd have enough room and that there'd be some spare I/Os, so being able to do this with the n800 is very impressive!!