CDMA Timing

GPS-synchronized products require you to install a view-of-the-sky antenna.
CDMA-synchronized products work great with the antenna inside your building, just like your cell phone.
(No subscriber fees required.)

Cell Tower
CDMA cell phone towers
transmit the timing signal.

The vast majority of precise timing products use GPS as their timing source.  These products require an antenna installed with a large view-of-the-sky.  Installing and maintaining the antenna can range from being merely a nuisance to being impossible.  In many downtown locations running a cable to the roof can cost several thousands of dollars and leasing rooftop space can cost hundreds of dollars a month.

How Is CDMA Used For Timing?

Our products harness the accuracy of GPS via CDMA signals used by digital cellular/PCS telephones.  Each CDMA base station has at least one GPS receiver because its' transmissions must be precisely synchronized within ten microseconds in order for the cell phone system to work properly.  Our products synchronize themselves to the CDMA base station transmissions, which means they are also synchronized to the GPS transmissions.  So, in effect, CDMA base stations act as GPS repeaters for precise timing applications. That's why we sometimes call it "Indirect GPS".

Where Are CDMA Signals Available?

These very reliable signals are easily received inside buildings and are extensively available throughout the U.S.A., China, Hong Kong, Japan and Korea.  If you are located in one of these areas then chances are good that you have CDMA cellular/PCS coverage.  If in doubt contact us.  You can also check the worldwide coverage map at  Any area listed on the charts with "Type of System" shown as 800 MHz or 1900 MHz will probably work with our products.  (If the "Technology" column shows LTE, this will NOT work with our products.)


How long will CDMA be Around?

CDMA service in the United States is currently provided by Sprint and Verizon.  As of August 2019, Sprint has merged with T-Mobile and has not announced any forthcoming changes to their CDMA network.  Verizon plans to discontinue CDMA cell phone service by the end of 2020 but continue service for its M2M partners through the end of 2022 with a thinner level of coverage.

CDMA-based network time servers acquire a UTC time sync from signals broadcast from a CDMA base station.  The Verizon signal is acquired via the North American Cellular (NAC) channel set and Sprint via the North American PCS (NAP) channel set.  If a CDMA base station is operational for phone service or M2M communications, it will broadcast the time and sync signals required by EndRun's CDMA network time servers.  The factory default channel set today in EndRun products is NAP due to the anticipated longevity advantage of Sprint's CDMA network .  

Sprint's 2014 Network Vision project completely upgraded 38,000 cell sites with plans to maintain its CDMA network for the long term.  We are unaware of any statements from Sprint since then regarding the future of CDMA but we are anticipating service to be available through at least 2022.  We have had unconfirmed reports that Sprint is contemplating discontinuance of CDMA in 2023 time frame.

In July 2019 Verizon spokesperson Howie Waterman confirmed to Light Reading that Verizon has pushed out the discontinuance date for CDMA cell phone service from December 2019 to December 31, 2020.  Some major M2M vendors that are in the Verizon Partner program have also announced that Verizon will continue CDMA service to their systems through 2022.  Network coverage could change post-2020, however, as some CDMA spectrum is re-farmed for LTE and 5G.

Reference Articles:

Light Reading:  Verizon Delays 3G Network Shutdown
Light Reading:  Verizon to Keep 3G Network Running for Some Enterprise Customers
Telecom Engine:  Sprint to Continue Supporting 2G for M2M Customers
SecureCom Wireless:  CDMA M2M products will have service until Dec. 31, 2022
Honeywell AlarmNet:  Verizon CDMA Activations UPDATE for AlarmNet Accounts