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Media giant Comcast Corp. (NASDAQ: CMCSA) on Thursday announced the launch of its Xfinity Mobile wireless service, putting the company in competition with established carriers like AT&T, Verizon, Sprint and T-Mobile. One day earlier, Alphabet Inc.’s (NASDAQ: GOOGL) YouTube kicked off its first foray into pay TV, launching YouTube TV in five U.S. cities. Does either of these new services stand a chance of being a big success?

In order to subscribe to Comcast’s new wireless service, a customer needs to have a subscription to Comcast’s broadband service. The company is not building out an entirely dedicated cellular network, however. Instead, it is taking advantage of its existing network of Wi-Fi hotspots to deliver wireless service when a customer gets within range of the hotspot.

The company hopes to beef up revenue. Comcast already has more broadband than cable customers, so the move makes sense both for the company and for its customers. Time will tell.

YouTube’s has entered an already crowded pay-TV business. Dish Network’s Sling TV, Sony’s PlayStation Vue and AT&T’s DirecTV Now are already offering similar services, and Hulu is preparing one of its own.

YouTube’s big advantage is name recognition and around 1 billion existing users. Sling TV, with about 1 million paying subscribers, is the current leader in subscriber numbers, but that could change quickly with the 800-pound gorilla now entering the fray. YouTube’s other big advantage is real-time TV streaming from the major networks, as well as local and regional programming. No other paid streaming service currently offers that.

As with Comcast’s wireless service, there is significant potential for YouTube TV, but the company needs to expand as rapidly as possible to take advantage of its unique market power and live-streaming service.