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Explained: why a CDMA iPhone needs a SIM slot

updated 08:45 am EDT, Wed October 20, 2010

CDMA iPhone 4 may need SIM for Japan and Korea

The appearance of what's claimed to be a CDMA iPhone prototype has raised the possibility that it might be a dual-mode CDMA/GSM phone. We've heard rumors to the contrary, however, and Electronista has reason to believe that Apple's handset is indeed CDMA-only. Read on to learn the relatively simple explanation and how Apple may sell the CDMA iPhone outside of the US.

In the US and (before Bell and Telus switched) Canada, phone subscribers don't see any slots on their devices because they adopt the original spec for CDMA information, which didn't offer removable user identity cards. This works in contract-focused North America, where people rarely switch from their current phones or providers until their contracts expire.

Many CDMA carriers outside of the continent, however, use either CSIMs (CDMA Subscriber Identify Modules) or older R-UIMs (Removable User Identity Modules). These not only let CDMA phone users move their account to a different CDMA phone easily -- a more common event abroad -- but can even work inside GSM phones if necessary. Apple may need to use a very compact CSIM to take up no more space than a standard micro SIM but, if so, could have a device that's cosmetically identical to the existing model, even if there's no GSM hardware inside.

While Verizon (and potentially Sprint) is likely the main target for any CDMA iPhone, the carriers that use CSIMs or R-UIMs are also some of the most important to Apple's international expansion. Some key CDMA networks relying on the cards are larger than the GSM providers the iPhone has had to use so far. China Telecom is larger than China Unicom; Japan's KDDI has traditionally been larger than SoftBank; South Korea's SK Telecom has usually been bigger than KT. And while Vodafone was an important coup for India coverage, Reliance and Tata Teleservices are both on CDMA and can use removable cards.

As such, we suspect that the N92 prototype not only has the rumored CDMA despite the slot but may virtually need it to fill out its intended role. Apple has repeatedly said that it wants to make as few iPhone variants as it can, and including a CSIM slot would guarantee that Apple could reach as many of the 547 million total CDMA subscribers as possible.


An example of a CSIM from Japan's KDDI

By Electronista Staff


  1. snappy22

    Fresh-Faced Recruit

    Joined: Oct 2010


    comment title

    Are you outsourcing grammar and spellchecking of your articles?

  1. eXtensions

    Fresh-Faced Recruit

    Joined: Jul 2010



    In Thailand I use a CDMA modem as a standby. It is supplied by a company called HUTCH and this is a Chinese company. All of these devices (and the CDMA phones here - most are GSM) have slots for SIM cards. Asia is a big market of course.

  1. aristotles

    Grizzled Veteran

    Joined: Jul 2004


    CSIM == ASIAN market, not Verizon or Sprint

    Why do you Americans keep on thinking that it is going to Verizon? Verizon markets devices directly to consumers and puts their V-cast c*** on all of their devices. Apple markets directly to consumers and would never allow a V-cast store on their iPhone.

    Compared to the Asian CDMA market, Verizon is a small pond.

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