The multistream service gives consumers the ability to stream on up to three devices simultaneously in or outside the home.

New Sling TV customers can trial the multistream service free for seven days and with no annual contract.

Sling TV's existing single-stream service -- which launched in the first quarter of 2015 -- includes content from Disney and ESPN Networks, but the multi-service stream does not.

A ESPN spokesperson said: “We are in active discussions with Dish about their multistream Sling TV service but we have yet to reach an agreement.”

MoffettNathanson Research says Sling TV service totals 523,000 subscribers. 

The new service includes Fox Networks Group channels -- Fox Broadcasting, Fox Sports, FX, and National Geographic Channel. Other multi-stream programmers include AMC, A+E Networks, HBO, Turner, Scripps Networks Interactive, EPIX and Univision. 

Key to the effort are local TV station markets. 

Customers who subscribe to the beta multi-stream service will have access to local Fox broadcast content, live and on-demand in 17 markets: Atlanta, Austin, Charlotte N.C., Chicago, Dallas, Detroit, Gainesville, Fla., Houston, Los Angeles, Minneapolis, New York, Orlando, Philadelphia, Pa., Phoenix, San Francisco, Tampa, Fla. and Washington, D.C. 

It can be purchased with or without the current Sling TV single-stream service. Sling TV’s single-stream service can be purchased with or without the new multi-stream service for $20 per month.