The Light Phone can be used as a secondary phone in a few different ways depending on your needs.
Swapping SIM Card: If you have a primary phone setup with a Light Phone supported carrier then you may be able to simply put your current SIM card in your Light Phone whenever you want to use it. This will allow you to maintain one number. Please be sure to restart the Light Phone anytime you put a new SIM card into the phone. Note: iMessage needs to be disabled for iPhone users so that the carrier receives incoming messages as SMS (green bubble).
NOTE: If your smartphone ONLY support eSIM, you will not be able to simply swap the SIM card between the two phones (i.e. iPhone 14+). The Light Phone III has eSIM technology, though that feature is still under development.
Second Number: If you'd like the Light Phone to have it's unique own phone number, like a "work number" or a "friends & family number," you may get a second SIM card for your Light Phone either from Light's own plans or by going directly to a carrier of your choice. The Light Phone in this situation would use its own unique number, independent of your other phone device, meaning that texts/calls do not sync across devices. You can set up call forwarding (please contact your carrier for specific information).
Personal Hotspot: When using the Light Phone as your primary device, you can set up a personal hotspot so that in certain situations you would be able to use another device like a laptop, tablet or old smartphone to access the internet on the go.
Carrier Services: Some carriers offer ways to maintain one number across multiple devices. These services usually involve a small fee added to your current phone bill. Once you’re signed up for a number share service, the carrier will send you a SIM card for your Light Phone.
Currently the phone works with T-Mobile - Digits: https://www.t-mobile.com/offers/t-mobile-digits .
It will eventually be compatible with Verizon NumberShare as well, but it is currently not supported. (We do not have an accurate timeline for when to expect this to work unfortunately it is out of our control: https://www.verizonwireless.com/support/numbershare-faqs/ )
iMessage note: Apple’s iMessage service is proprietary to them and can’t be offered on any other devices. We recommend disabling iMessage if you are swapping your SIM. When someone sends you an iMessage to your Light Phone number or while your primary SIM card is in your Light Phone, then it will send a ‘green’ text bubble.