T46s Veriizon as LAN only phone?

[Desertfabworks]

I got several T46s Verizon phones that were being tossed as part of an upgrade. I did factory resets on them and wanted to see if there was a way I could use then on my network as phones without external service. So just local in different parts of my business. So if I wanted to talk to someone in the shop I could connect to the shop phone but all on a network connection? Hope that is clear as mud Thanks