For the most part, cable TV providers began offering voice service over broadband
at a time when VoIP was a trusted solution. Because it was already an accepted technology,
most cable providers have centralized softswitch architectures. They are not
saddled with the burden of supporting the hundreds of local legacy switches. Legacy
switches refer to the older, less-efficient circuit switches connected to subscribers who
have analog telephones. Furthermore, although they have traditionally used standards
developed by the cable industry’s standard setting organization, CableLabs, they now
use standard IP protocols for their VoIP infrastructure.
