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CompTIA A+ Certification All-in-One Exam Guide

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PRL, PRI, and Baseband Updates As mobile devices travel, they

frequently have to pass through areas that don’t have strong signals, or into

areas that the carrier does not service. When a mobile device connects to

different carriers’ networks, we say it is roaming; roaming may result in

additional service charges, depending upon the carriers involved.

Your phone’s firmware will receive occasional automatic updates to its

Preferred Roaming List (PRL) from the carrier; the PRL is a priority-ordered

list of the other carrier networks and frequencies it should search for when it

can’t locate its home carrier’s network. Updates to this list are sent via your

phone’s cellular connection (called baseband updates, or over-the-air

updates) or, in some cases, through firmware updates during normal

operating system and firmware upgrades via synchronization.

CDMA devices may also receive product release instruction (PRI)

updates, which modify a host of complex device settings. Don’t worry about

specifics, here—these settings can pertain to the intricacies of many functions

such as GPS, cellular connectivity, and messaging—but instead focus on the

fact that carriers use these product release instructions to ready the device for

deployment on their networks, enable the network to route calls or messages

to the device, and more. As such, PRI updates may be needed if the network

is evolving during the lifetime of a device, the device needs to be moved to a

new network, or the device has a new owner.

EXAM TIP PRL and PRI updates are handled automatically during

firmware/OS updates. They are only for CDMA networks. No one but the

nerdiest of nerds will ever see these updates.

IMEI, ICCID, and IMSI There are three particular identifiers you will

need to understand both for the exam and for real-life management of mobile

devices. The International Mobile Equipment Identity (IMEI) number is a 15-

digit number used to uniquely identify a mobile device. IMEI numbers are

unique to devices using the Global System for Mobile Communications

(GSM) family of technologies, including its present-day descendants: 4G

LTE and LTE-Advanced. You can typically find this number printed inside

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