For starters, here's what the C4c looks like:

An Arris spokesman tells Cable Digital News that the C4c takes up seven rack units (RUs), making it about half the size of the C4, Arris's chassis-sized CMTS flagship.
Those two products will complement the C3 "pizza box" CMTS that isn't expected to support specs beyond Docsis 2.0.
As for the C4c, Arris hopes it will address the needs of smaller systems that want to upgrade to Docsis 3.0 but don't require as many ports as the C4.
Arris expects the C4c to become commercially available this summer, but has not specified when it might submit the new product to CableLabs for official qualification testing.
But already in the C4c's favor is the fact that it uses the same software and linecards as the C4, which has already obtained CableLabs' Bronze-level qualification. Arris has not indicated when it will shoot for Silver qualification, which introduces upstream channel bonding to the mix, or go for Full qualification. (See Cisco, Arris & Casa Make the CableLabs Grade.)
— Jeff Baumgartner, Site Editor, Cable Digital News