GPS Location Accuracy Advisory
Starting April 6, 2019, GPS enabled devices will go through a clock rollover event (GPS Week Number Rollover (WNRO)). This is a global GPS issue and not restricted to the wireless industry. However, the WNRO may affect the accuracy of GPS location services on a very limited number of mobile wireless devices.
Enhanced 911 is an example of a service that uses location details, and this location detail comes from various sources including GPS. In the event that GPS does not work properly, 9-1-1 calls from improperly configured devices will still reach the appropriate emergency call centre, but inaccurate or no location datamay be associated with the call. While other methods for determining location, such as cell tower location, do not rely on GPS data, they are typically less accurate.
While most mobile wireless devices are properly configured, a very limited number of devices are known to be affected. Canadian wireless service providers have worked with device manufacturers to identify affected devices and are reaching out to customers using devices known to be impacted.
For further information specific to your wireless service provider please refer to the information below.
- Bell – customers can visit Bell.ca/GPSinfo for more information.
- BellMTS – customers can visit BellMTS.ca/GPSinfo for more information.
- Eastlink – customers who have been contacted by Eastlink regarding potential impacts to location accuracy for 9-1-1 calls may contact Eastlink at 1-888-345-1111 for more information.
- Freedom Mobile – customers who received a message about their wireless handset can call 1(800) 637-6828 for more information or to explore device options.
- Koodo – customers can visit here for more information.
- Lucky Mobile – customers can visit LuckyMobile.ca/GPSinfo for more information.
- PC Mobile – customers can visit PCmobile.ca/GPSinfo for more information.
- Public Mobile – customers can visit here for more information.
- Rogers (including Fido and Chatr) – customers can visit here for more information.
- SaskTel – customers can visit here for more information.
- Solo Mobile – customers can visit SoloMobile.ca/GPSinfo for more information.
- TbayTel – customers can visit tbaytel.net/gpsinfo for more information.
- TELUS – customers can visit telus.com/GPSinfo for more information.
- Videotron – customers can visit http://bit.ly/news_GPS for more information.
- Virgin Mobile – customers can visit VirginMobile.ca/GPSinfo for more information.
- Xplore Mobile – customers can visit https://www.xploremobile.ca/gps-week-number-issue for more info.
What is the GPS Week Number Rollover?
The GPS Week Number Rollover refers to the limitation of values in the GPS message format counter. After the counter reaches the 1024th week, it will reset to zero, which is what will occur as early as April 6th. Properly configured devices should not be affected. However, some hardware chipsets incorrectly handle the date rollover. Because GPS Time is used for device location determination, an improperly configured device may result in inaccurate or no GPS location information.
For further information on the GPS WNRO, a U.S. Department of Homeland Security memorandum describing the issue is available here.