I recently wrote this email in response to this very question and it occurred to me that I’ve answered this question a number of times. It seems, therefore, that it might make a good blog post for others looking for this information.

The companies mentioned in this post are Canadian since I am Canadian, but the companies are not important. All cell phone companies in the world fall into two categories: CDMA or GSM. If you’re in doubt as to which companies in your area fall into which category, just phone ‘em up and ask them. Or Google it. I mean, really…just Google it.

Here we go…

If you’re buying a GSM one (Rogers, Fido) you can buy an unlocked handset on eBay and then just buy a Rogers or Fido SIM card and stick it in. Or you can buy a specific Rogers or Fido one that is not unlocked and still buy and stick a SIM card from the applicable carrier into it.

If you’re buying a CDMA one (Telus, Bell) you have to specifically buy a Telus or Bell phone that matches the network you want to activate it on.

Bottom line is that the providers DO NOT want to activate any handset that is not their own. The market is such that there is no money in the actual handsets and they make all their money in subscriptions. They therefore have a gentleman’s agreement in place to not activate each other’s phones.

In the case of CDMA phones, there is no SIM card – the network talks directly to the handset so you must have a handset that belongs to the provider that you want to activate with. This is my situation so I must always buy Telus handsets since I am on a Telus contract. There is no concept of the word “unlocking” with respect to CDMA phones. That term only has meaning when talking about GSM phones (see below).

In the case of GSM handsets, there is a SIM card and the network talks to the SIM card and therefore has no knowledge of the handset the SIM card is plugged into. There are two possible scenarios with used handsets in this case. Since the GSM architecture prevents the provider from knowing what handset their SIM card is plugged into, they program the actual handset to only accept their SIM cards. This process is the “locking” that everyone talks about. The handset is “locked” to only accept a SIM card from the provider who issued the handset. If you buy a locked GSM handset you will only be able to activate it with the provider that issued the handset.

The other GSM scenario is that you buy an “unlocked” handset. This is a handset that has been modified to accept any SIM card from any provider. With this type of handset you can walk into any GSM provider, buy a SIM card for $25 (ish) and activate on their network. You don’t want to actually tell them that you want it for an unlocked phone, though, as that will most certainly violate their terms of service. Just tell them you have one of their handsets and you need a new SIM for it. Or buy one online to avoid all questions.

Hope that helps!

Related articles by Zemanta

• Bell, Telus to sell iPhone next month: report (cbc.ca)

Tags: Add new tag, bell, Canada, Code division multiple access, google, GSM, Mobile phone, Subscriber Identity Module, telus

Some related posts:

• January 21, 2010 -- Looking for Blackberry OTA Backup Solutions (1)
• October 17, 2008 -- Telus and Bell Going GSM HSPA (2)
• January 16, 2010 -- JungleDisk: Amazon S3 For Windows, Mac & Linux (0)
• January 14, 2010 -- GoGrid: Instant Servers and Cloud Storage (0)
• January 6, 2010 -- Blog Reboot! (1)