Cable operators have high hopes for advanced services, but a pair of telephone companies reminded them this week that they don't have the luxury of operating in a vacuum.Verizon ( VZ) said Monday that it is expanding a combined telephone and video service package to Florida and Texas, bringing the bundle to a total of eight states. Separately, AT&T ( T) said it would introduce a voice-over-Internet-protocol-based phone service to customers in New Jersey, the first step of a planned nationwide VoIP rollout. The two plans erect another hurdle in front of big cable operators such as Time Warner ( TWX), Comcast ( CMCSA) and Cablevision ( CVC), which are intent on bolstering their slow-growing core cable franchises with a growing array of services. Verizon's offer -- in conjunction with the DirecTV ( DTV) home satellite service -- represents yet another source of competition for cable's core multichannel video business, which has been showing minimal growth over the past few years. Meanwhile AT&T's product, which requires a high-speed Internet connection, adds an established, name-brand competitor to the telephone service that major cable operators are in various stages of rolling out. It thus poses one more threat to one of the several revenue streams that operators are looking to to counter the anemic basic business.