What is a PRL?
A PRL, or Preferred Roaming List, is a database the carrier loads onto a CDMA phone. It tells the phone which networks it's allowed to use and which to prefer, both in its home area and when roaming on partner networks. Carriers that ran CDMA networks, such as Verizon and Sprint in the United States, used PRLs on their phones.
What's in it
- System table: network identifiers (SID/NID) the phone may connect to, each marked as preferred or not and ranked by priority.
- Acquisition table: the frequency bands and channels the phone should scan to find those networks.
When the phone powers on or loses service, it works through the list to find the best allowed network. An outdated PRL can leave a phone on a weaker partner network, roaming when it shouldn't, or without service where the carrier has added coverage or roaming partners since the list was loaded.
Updating the PRL
PRL updates were delivered over the air. Depending on the phone and carrier, the user picked an option such as Update PRL in the phone's system or carrier settings, or dialed a short code the carrier provided, and the phone downloaded the new list. Updating the PRL was a standard step when a CDMA phone had poor reception, roamed unexpectedly or had trouble after travel.
The same menus often offered PRI (product release instructions) updates, which change carrier configuration settings on the phone, and profile updates for the data account. These are separate from the PRL.
PRL as a legacy technology
GSM, UMTS, LTE and 5G phones don't use a PRL; they rely on network selection lists stored on the SIM or eSIM. U.S. carriers have shut down their CDMA networks, so PRL updates now matter mainly for old devices and older study materials.
PRI can also mean Primary Rate Interface, an ISDN telephone trunk service for businesses, which has nothing to do with phone updates or the PRL.
For the CompTIA A+ exam
PRL doesn't appear in the 220-1201 objectives or its acronym list. Core 1 objective 1.3 covers cellular data, 3G/4G/5G and SIM/eSIM configuration instead. You may still see PRL updates in older practice material: the idea is that the carrier pushes an updated list of preferred networks to a CDMA phone over the air.