We’ve already addressed the topic of unlocking devices in FCC filings (such as this one) and blog posts, including this one that offers a list of unlocked devices available today. But as an engineer who has dealt with these issues at Bell Labs from the industry's early days, I felt it was important that I explain some of the technological challenges that exist with unlocked devices.
The engineering reality: An unlocked phone doesn't necessarily mean an interoperable phone, or one that you can take to any carrier that you want and here's why.
As you know, wireless technology relies on spectrum, which are the radio frequencies designed for specific uses. When spectrum is purchased at auction, the bands are divided into useable sections. Since the spectrum allocation is different, there's no uniformity in the U.S. across all of the carriers. Quite simply, there is no device that could work across all bands, allocations and technologies. In order to create such a device, it would be much bigger than we're accustomed to since it would have to include a number of radios and corresponding parts that increase size and reduce battery life (think Gordon Gekko phone or for those of you who are younger, Zack Morris phone).
In the U.S., there are a variety of "flavors" of technology too. There's GSM, GPRS, CDMA, EV-DO, UMTS, HSPA (and HSPA+), LTE and soon VoLTE. These technologies sometimes work with other carriers, but sometimes, there may be devices that may only work in a carrier-specific band of spectrum.
To add to the different technologies then there is the identity management structure. Mobile devices that may operate on carriers' networks may use SIM, IMSI, and IMEI, where others may use MEID and ESN.
As if this wasn't complicated enough with the different networks and identity management, there's also operating system, device hardware, security, optimization and cloud differences. Here's a quick explanation of each one of these:
- Operating Systems – Public mobile networks may be at different releases of OS and have OS variations across networks, which may cause incompatibilities
- Device Hardware – Networks may have a variety of device hardware vintage interoperability, which simply means it may impact how a device interacts with the network
- Security Solutions – Carriers may use a variety of security solutions to protect networks and offer proprietary products to their customers too (e.g., anti-virus, VPN, etc)
- Optimization: Phones are optimized for a particular carriers' network, for example, towers and data roaming partners
- Cloud-back-up – If consumers choose to store information on the cloud, the different cloud options may prevent someone from transferring that information to another carrier (e.g., restore to device from carrier A cloud over carrier B network)
Yet these are only a few of the technological challenges that exist for the post-paid (or contract) and prepaid consumers. In addition, those who rely on prepaid wireless services typically cannot transfer their devices to another carrier. Prepaid providers may not allow individuals to bring in their own devices either due to the proprietary software used to manage the customer's usage or customized features (e.g. parental controls).
It's thanks to the diversity and highly competitive nature of the U.S. wireless market that consumers have benefited greatly since the U.S. leads the world in 4G/LTE and smartphone deployment. At the same time, it also means that we have some challenges associated with the wide variety of options that ought to be considered so that consumers will have realistic expectations about what is possible when unlocking their devices.