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What is a RUIM Card?

By R. Kayne
Updated May 16, 2024
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A removable user identity module (RUIM or R-UIM) card is an identification chip for cell phones that work on Code Division Multiple Access (CDMA) networks. A RUIM card stores a user's personal information, such as his or her name and account number, phone number, address book, text messages, and other settings. These cards can be swapped between compatible phones, so the user's information and settings are easily transferred. In many cases, a RUIM card can also be used in a phone designed to work on the Global System for Mobile Communication (GSM) network.


To activate a CDMA phone that uses an RUIM card, only the card must be activated. Once active, it can be used in any compatible handset by simply removing the card and inserting it into another phone. The new phone is then able to make and receive calls on the user's account.

Users can switch between several phones or borrow a friend's compatible phone to make a call with his or her own RUIM card. If the user switches to another phone service provider (also called a carrier) and wants to keep the old phone, a new card from the carrier can be inserted into the existing phone. The existing phone must be unlocked and compatible with the frequency band of the new carrier for this to work, however.

It's important to note that, for the RUIM card to work in a new handset, that phone must either be from the same cell phone service provider or unlocked. In some countries, like the US, a phone handset is usually locked to a particular carrier, which means that only RUIM cards from that same carrier can be used in these handsets. An unlocked phone is one that has had this limitation removed; any card from any carrier can be used in an unlocked phone.


The RUIM card was designed to replicate many of the advantages of the Subscriber Identity Module (SIM) card on the GSM network. Phones on the CDMA network that do not use RUIM cards store all of the user's information in the phone itself; if the user wants to change phones, he or she has to go to the cell phone service provider, who will transfer the information to the new handset. GSM network phones use SIM cards, which store all of the user's information, so activating a new phone is often as simple as moving the card from one handset to another.

CDMA phones that use RUIM cards share this ability to swap information between phones. The card is the same size and shape as a regular SIM card, and typically includes a version of the SIM software, which means that it can be used in GSM phones. As with switching cards between CDMA phones, however, the GSM handset must be unlocked for a RUIM card to work with it. An RUIM card in a GSM phone might not work in all locations, because different regions use different cell phone frequencies.


Security is a major concern for people who use RUIM cards since they hold all of the user's personal information. Most RUIM cards require — or can be set to require — that the user enter a personal identification number (PIN) before the card can be used. When a phone containing the card is powered on, the user must enter this number to use any of the phone's features other than emergency calls. If the user enters the wrong PIN multiple times in a row, the phone will become blocked and no longer accept new tries.


The CDMA network has the largest number of subscribers primarily in Asia and North America, but not all service providers use phones with RUIM cards. They are much more common in China and other Asian countries than they are in the United States, for example. There are a number of different reasons for this; some experts suggest that US cell phone users do not switch between phones as often as people in other countries, and so don't need this feature, while others argue that US carriers don't have any incentive to allow users to switch between handsets more easily.

The Future of RUIM

CDMA and GSM are second-generation (2G) technologies, which was designed primarily for voice calls. With the increase in data usage by users, many carriers have upgraded from 2G technology to 3G, which can transfer data more quickly; the two main competing 3G technologies are CDMA2000® and Universal Mobile Telecommunications System (UMTS). Although UMTS works on the Wideband CDMA (WCDMA) standard, it operates on the same core network as GSM, and is not compatible with CDMA or CDMA2000®.

As development continues, however, most carriers — including those using CDMA and CDMA2000® — are upgrading to 3GPP Long Term Evolution (LTE), which is based on GSM and UMTS. All LTE phones use SIM cards, so new handsets that use this network from any carrier must have that type of card. This means that RUIM cards, which do not work on LTE, will likely eventually become obsolete.

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Discussion Comments

By anon931401 — On Feb 08, 2014

Does the Samsung SCH-R480 CDMA phone use a R-UIM card?

By anon327399 — On Mar 27, 2013

What if my cell phone does not use a RUIM Card? I have CDMA phone but was given a GMS phone as a gift. I want to use The GMS phone with my service but not able to. So here is my question: can I have all my information placed on a RUIM card and put it into the GMS phone?

By anon317560 — On Feb 02, 2013

I touched "password on ruim:" and it asked for the password. I entered it and now it says it's wrong and it says there's no sim card. Please help!

By anon289879 — On Sep 06, 2012

I have a CDMA2000 Data Card. It doesn't work with a SIM card, so I don't know what to do. Please help me!

By anon254678 — On Mar 14, 2012

I have a CDMA line and I want to have my line swapped with another RUIM card without having to pass through my service provider.

By anon192875 — On Jul 03, 2011

how can I use a uim card in pakistan? please help me.

By anon127104 — On Nov 15, 2010

I have a Intex GSM mobile but after insert SIM showing insert UIM Card. where can I get it?

By mattu2175 — On Sep 15, 2010

how can i convert a gsm phone into a cdma?

By anon95162 — On Jul 11, 2010

I have a Pantech C300 (GSM) phone which I like very much. Unfortunately, ATT's coverage in rural areas stinks! I have used a CDMA phone (Sprint network) which is better. I'd love to be able to use the Pantech all the time. Is there a way to make the Pantech signal roam into Sprint or Verizon?

By anon67343 — On Feb 24, 2010

i want an R-UIM card now. Where can I get one?

By anon55684 — On Dec 09, 2009

a gsm phone can never be converted to a cdma and vice-versa. although ruim cards are for cdma phones, cdma phones in USA don't use these cards and the information is simply programmed on the phone itself, so there is no way of having a ruim card on a USA cdma phone.

By anon40168 — On Aug 06, 2009

I want an R-UIM card now. Where can I get one?

By anon39753 — On Aug 04, 2009

i have sony ericsson's w54s. i got it from japan but the problem is that it supports RUIM and here where i live, SIM service is running, so how can use this cell phone with SIM service?

By anon38189 — On Jul 24, 2009

I am currently using a phone with a SIM card, but I want to get a CDMA phone from America. Problem is that I don't live in America so using the phone from where I live will be a problem since *if* I get the phone I need to get a new number and all. But what if I just get a RUIM card from my country and stick it in the phone, would it be possible to use it then?

By anon22858 — On Dec 11, 2008

I have an alltel phone. I don't think alltel uses sim cards. Is there any way I could possibly use a sim card though?

By anon18392 — On Sep 22, 2008

I bought a Nokia 2505 in Morocco last summer and now i want to unlock it for use in the Netherlands. Is that possible or does a CDMA-phone never work in a GSM-country?

By anon15482 — On Jul 13, 2008

hello, im ed, i have this ZTE WP960CD wireless phone and i discontiniued the services, so they gave me the phone. my question is, is it possible that i insert a SIM card to the phone to make it work? thanks, ed

By anon14851 — On Jun 25, 2008

who manufactures the phones with cdma technology? a lot of different companies (Samsung, LG, Motorola, etc...) But the company who makes MOST of the CDMA chipsets is QualComm.

By tiriviere04 — On May 29, 2008

Sincere salutations to all at WiseGeek;

1-/Can my current phone information be transferred onto an R-UIM/CSIM card from my PC via USB for future use on different phone supporting both GSM & CDMA?

2./If so would you be able to provide guidance as to software and cards needed for such a process?

By anon13263 — On May 23, 2008

I bought a ping mobile recently and while browsing around it, I pressed "Restore Factory Settings". Since I did that it's been saying, "Invalid R-UIM card." What does this mean and how can I access my mobile phone like I previously did. -Preity

By anon12569 — On May 09, 2008

who manufactures the phones with cdma technology?

By servechilled — On Apr 11, 2008

@apocali - You can't convert a GSM phone to a CDMA phone. CDMA and GSM are completely different technologies and use different onboard components inside the phone. However, technically you could swap out the circuit board in the phone from GSM to CDMA or the other way around. But that's way too much cost and hassle, and would potentially break the phone in the process. So, you either go with a GSM carrier or CDMA.

By anon5348 — On Nov 21, 2007

Can R-UIM cards go into a sanyo katana and how? And if the answer is yes to the previous question, can I get a blank card and card reader and put all my cdma network info on it so I can use it on an iphone?

By apocali — On Sep 02, 2007

how can i convert a gsm phone into a cdma?

or what component locks a phone to be a cdma or a gsm and can it be changed?

By anon2284 — On Jul 06, 2007

what is the process once your phone cellphone is unlocked and you sign-up with another carrier? in order to do this do this is it subject to credit approval with your new service provider?

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