Cable and telco operators, satellite-TV providers, TV networks, programmers and a host of other media and communications companies have come out in force at the Supreme Court in support of marriage equality.

Cablevision, Comcast, Cox, Verizon, AT&T, CBS, DirecTV, Google and Twitter are among the 379 organizations joining in an amicus brief in the High Court review of Obergefell v. Hodge, in which the court has the chance to rule that all states should both permit and recognize same-sex marriages as legal.

"More than 70% of Americans live in a state that celebrates and recognizes same-sex marriages," the brief says. "But many states continue to prohibit same-sex couples from marrying, and decline to recognize the valid, existing marriages of citizens married to a spouse of the same sex. This fractured legal landscape harms employers and employees alike."

The companies argue that marriage bans adversely impact their ability to "attract and retain a talented workforce." Additionally, given that some states recognize same-sex marriages and others don't, such a bifurcated regime imposes "unnecessary costs and administrative complexities on employers, and requires differential employer treatment of employees who are similarly situated save for the state where they reside."

Verizon, in a blog signalling its support of the brief, said, "Calling on the Supreme Court to finally make clear that all couples share the right to marry is consistent with our long-standing commitment to diversity and our support of the LGBT community."

The Supreme Court is scheduled to hear oral argument in the case April 28. The two questions at issue, according to scotusblog.com, are whether a state has to license marriage between two people of the same sex and whether a state has to recognize such marriages performed by other states.

Here's a list of all the companies signing on to the brief.