All Nextel customers will have a phone that uses a sim card.  All new phones that have been released will use and include a 128k 600 contact sim card.  Any Nextel phone that uses a sim card will accept either a 32k, 64k, or 128k sim card.  All Nextel sims are white on one side and another color on the other side.  The 32k Condor Sim Card is grey on the other side.  the 64k Falcon Sim Card is Yellow on the opposite side.  Lastly, the 128k Black Sim Card is Black on the opposite side. 

The 32k sim can be used in any Nextel phone that accepts a sim card starting with the series i** such as the i35, i60, i90, i95 and more.  Any model that is an "i" followed by two digits all the way up to the newest phones including the i870, i580, and i880. 

The 64k sim can be used in all i*** series phones.  These models include the i530 i275, i730, i830, i860 and everything since then including the newest phones that have just come out. 

The 128k sim can be used in only the newest models out including the i836, i850, i870, i580, i880, i325, i325is, i275, i930, i920 and a few more.

We have been selling Nextel phones, accessories, and sim cards for several years on eBay and have quite a bit of knowledge on the subject.  We have had many members and customers tell us that Nextel told them that using a type of sim card that didn't originally come with the phone can do damage to the phone.  Out of the thousands of sim cards that we have sold, we have NEVER personally had a customer tell us that their phone was damaged because of this reason.  We believe it to be a falsity and can say with thousands of experiences to back it up. 

Hopefully this clears up some of the questions you may have been having regarding if your sim card will work in the Nextel phone you are looking at switching to.  IF YOU DID FIND THIS GUIDE TO BE HELPFUL, THEN PLEASE TAKE JUST A MOMENT OF YOUR TIME TO CLICK THE "YES" BUTTON BELOW AS THIS IS THE ONLY FORM OF POSITIVE FEEDBACK THAT WE CAN SEE FROM WRITING THESE GUIDES.  THANKS AGAIN!