The RBR10 has one ethernet port to connect to the modem and one ethernet port to connect to "anything else." The satellites have no ethernet ports at all. This is the least expensive mesh Orbi system. The data sheet makes this pretty clear: https://www.netgear.com/images/datasheet/orbi/RBK12.pdf The RBR50, in contrast, has three local ethernet ports on the router and four ethernet ports on each satellite.
That single port on the RBR10 router is clearly designed to allow connecting an inexpensive ethernet switch (8 ports for $25 is typical). If the VOIP phone is not located near the router, then this is the wrong WiFi system. Take it back.
