A shining success in recent years, cable’s VoIP service has stolen a healthy amount of telcos’ traditional landline customers while producing hale revenue and steady segment growth. But a troika of developments has produced storm clouds already threatening to dampen the industry’s cheery digital voice outlook. First off, AT&T‘s Detroit launch of digital service U-verse Voice affects mostly Comcast initially, but its planned rollout in other U-verse TV markets will likely assail Charter, Time Warner Cable and Cox as well. The telco plans to entice customers with the service’s features—including some that sync with wireless devices—and the resultant quad play, said a spokesperson, noting that direct marketing is underway in Motown. Still supremely confident in its own VoIP play, Comcast isn’t planning any combative marketing or advertising initiatives in the area, said a spokesperson. Also portending a possibly protracted legal battle is a seeming litigious streak from Verizon targeting major MSOs. The telco has filed in a US District Court in VA a patent infringement suit against Cox covering 8 patents related to VoIP technology. This after a similar beef with Vonage that resulted in a decision for up to $120mln in recompense to Verizon, which is similarly seeking from Cox monetary damages and an injunction against using said patents. The MSO declined comment. Consider this: the patents cited in the Cox case include the pair Vonage was found to have violated, and as many MSOs use similar VoIP architecture, a slap to Cox could have future implications for the entire cable industry. Lastly, Clearwire inked a deal calling for Nortel to deliver a complete carrier VoIP solution for the provision of residential voice service to its US customers. Clearwire already offers VoIP service in 37 of its 46 domestic markets but, importantly, the deal allows for the potential future delivery of converged fixed and mobile services. Although cable is well positioned in the VoIP space, increasing competition and the chance of very costly legal battles should be on the radar.