$500 via Verizon e-gift card (sent w/in 8 wks). Activation of 4G LTE/5G phone on One Unlimited for iPhone (all lines on account req'd on plan), 5G Do More, 5G Play More or 5G Get More plans req'd. Device must remain active for 45 days. $500 charge back if service cancelled w/in 12 mos or eligibility req's are no longer met. See vzw.com/bring-your-own-device for details. And for a limited time, we’ll waive your activation fee when you order through vzw.com or My Verizon app. You’ll see the one time charge waived as your “Due Today” amount at checkout.
The parameter you're after is called "REN". As the previous poster points out, the "612" model seems popular and it has an output rating of 5.0 REN. You can find the REN rating on the base of each phone -- add them together and as long as you're below the number indicated for your ONT, you're good.
A better way to solve this is to use a wireless phone system with a single base station. In this scenario, only the base station itself counts toward the REN total. Each individual wireless handset adds no additional line load.