"We actually believe the court challenge to this is quite strong," Stephenson said at a J.P. Morgan investor conference Monday in Boston. "We have a certain degree of conviction that these won't be the rules of the land going forward."
Shares of Dallas-based AT&T were gaining 1.1% to $34.72 on Monday, extending its 2015 advance to 3.4% compared to 3.1% for the S&P 500
In February, the Federal Communications Commission approved rules that classify Internet providers as public utilities, giving the commission broad oversight over them. The rules aim to support the concept of net neutrality, whereby broadband providers such as AT&T, Comcast (CMCSA) and Verizon (VZ) are not allowed to favor some Internet content users over others.
AT&T joined the legal battle against the new rules last month by suing the FCC.
Then, earlier this month, AT&T and telecom industry lobbying groups asked a federal court in Washington to prevent the FCC from implementing the new rules until rulings are made on various lawsuits challenging the commission's decision.
Stephenson said that the rules are likely to be modified in part because the FCC's leadership could change with a new administration, or by an act of Congress. The FCC's net neutrality rules were approved by a 3-2 vote in February along party lines.
"This needs to be done legislatively rather than through a 3-2 vote," Stephenson said. "Administrations change and FCCs change. Our investment thesis is that these rule probably don't remain as written right now."
FCC Commissioner Tom Wheeler in February argued that the agency had to take a firm step to preserve a "fast, fair and open Internet" to ensure that operators would not have unfair advantages.