Whistle 3 uses AT&T's 3G cellular network to send location tracking updates to your smartphone from anywhere across the United States. Regardless of which carrier provider you use for your smartphone, Whistle 3 communicates seamlessly by sending your smartphone updates via the Whistle app and/or via text messages at no additional costs.
In order for your Whistle 3 to function fully and share your pet's latest GPS location when outside your Safe Place(s), it must have a good AT&T 3G connection. Keep in mind that in some areas, 3G coverage can be affected by the environment (natural landscape/terrain, buildings, etc.) around your Safe Place(s) and can thus affect your Whistle 3's ability to receive and communicate a GPS location with your smartphone. See our Coverage support article to learn more.