What is ARP (Address Resolution Protocol)? This protocols main purpose is to identify network nodes MAC address using its IP. ARP creates database of discovered nodes in the network and saves it on local machine for future use.
Whenever one node of the network needs to know some other nodes MAC address, it broadcasts the ARP message to the network. Message contains ...
You can get in the situation when more POTS ports than 2 (like for this HGU type ONU) are needed. That could be a small office customer or building with more flats. It may also support a few TDM (time division multiplex) services such as DS1 or E1, via pseudowire emulation. This SBU from Fiberbit:
For example can have 16 FXS POTS ...