  Numerous advantages may accrue to ET from the use of probes for the
conveyance of information relative to the alternative of beaming information
electromagnetically from its home star system. However, probes would benefit
from a trans-galactic communications network to transmit information back to
their progenitor civilization(s) and throughout the Galaxy. A model for such
trans-galactic communications has previously been proposed, comprised of probes
linked together by relay nodes. The current paper refines that model,
specifying two types of probes or nodes, both part of a communications lattice.
The first type of cellular probe (CP) is statically associated with individual
stars, and the second type is a scout CP that traverses the galaxy surveying
successive star systems rather than permanently residing within any one of
them. CPs would communicate with adjacent CPs and, ultimately, through the
network of CPs, with their progenitor civilization(s). The question of whether
Oumuamua is such a flyby scout CP is considered. Search strategies for CPs are
suggested.
