I've noticed that the Straight Talk iPhone 5s/6 that use the Verizon network are locked to Straight Talk and you can't even use a postpaid Verizon SIM.
Because Straight Talk is selling phones that are activated on Verizon's LTE network which uses the lower 700 MHz band(band 13), it's technically illegal for them to sell phones locked to their network.
Same goes with Xfinity Mobile which is a Verizon MVNO, they lock phones to their network even though it's prohibited for devices in use on a band 13 network to be locked.
According to FCC regulations devices that are on a band 13 network cannot be SIM locked, this doesn't apply to devices that just have band 13 capability, only devices sold for use on a band 13 network and Straight Talk and Xfinity are both band 13 networks.
Then again Tracfone and Comcast are known for being incredibly shady so I don't put it past them to do stuff like this, but still, somebody should sue them.
Because Straight Talk is selling phones that are activated on Verizon's LTE network which uses the lower 700 MHz band(band 13), it's technically illegal for them to sell phones locked to their network.
Same goes with Xfinity Mobile which is a Verizon MVNO, they lock phones to their network even though it's prohibited for devices in use on a band 13 network to be locked.
According to FCC regulations devices that are on a band 13 network cannot be SIM locked, this doesn't apply to devices that just have band 13 capability, only devices sold for use on a band 13 network and Straight Talk and Xfinity are both band 13 networks.
Then again Tracfone and Comcast are known for being incredibly shady so I don't put it past them to do stuff like this, but still, somebody should sue them.