If I buy a iPhone 6 on eBay, does it have to specifically match for the service plan I'm getting?

So If my phone service is say verizon, do I have to get an iPhone specifically made for verizon plan. Does the sim card have to match or is it universal.

Depends if the phone is locked or not. If the phone is advertised as being locked to a certain network then it means it'll only work with that network unless you get it unlocked. Unlocked phones work on any network

Yes… Or sometimes… Its hard to tell

In some cases yes since the phones in some cases are locked to that carrier. So getting an AT&T iPhone for example would only work with AT&T SIMs.

In the case of Verizon though, unless things have changed, they are unlocked so its not an issue. If it is locked to another carrier, then it wouldn't work on Verizon or any other.

Though in the case of Verizon, it is a CDMA network & the SIMs are just for LTE data use, not calls/text like on a GSM carrier like AT&T/T-Mobile.