If you look at triband phones, many are 900/1800/1900...so beware.

Caveat: Nokia Phones not made for the US market cannot be repaired under warranty in the US. They must be repaired in the "country of origin". Buying phones on Ebay, IMHO is a crapshoot at best.

tiband hp like n90 can be used

Based on the phones offered by Immix they look to operate on both 850 and 1900 in the US. Make sure the phone has both 850/1900. Any "unlocked" GSM phone with those frequencies will work. Also, buy from someone with a lot of positive feedback. I have done this before and am very happy. If you will only be using voice and SMS you probably wont need to configure the phone. If you need to configure your phone for data or MMS Immex might be able to help you out. If you plan to use these features call Immix first to confirm that they will support the phone you want to buy for data and MMS. But like I said, voice calls should work immediately out of the box once your old SIM is in.

Chances are, your provider Immix is an MVNO (click for definition), and the most compatible phone would be branded for the service provider they "resell" in your market area. However, any unlocked GSM phone with the 850mhz & 1900mhz bands would work as a phone, you just might have trouble getting text and data to work on an unbranded, unlocked phone with an unknown service provider, that all depends on how good their customer support is and whether or not they will help you set up an unlocked phone. Maybe they're the best ones to ask, but that's what I know.

Hi. I am looking to buy some type of nokia flip phone on ebay. My current service provider is Immix Wireless. (it is unheard of) Would i be able to buy any SIM cell phone on ebay and put my old SIM card in it?? How do i know witch one to buy? Someone please help. It would be greatly appreciated
Thanks