The telecom chiefs were testifying before the US Senate Commerce Committee, which was trying to find out if the bankruptcy of WorldCom and problems at other telecom companies would affect services.
The committee also heard from the top US communications regulator, who also expressed his confidence that links would not be disrupted.
"I remain confident that we are not facing a crisis in the provision of services stemming from WorldCom's bankruptcy," said Michael Powell, chairman of the Federal Communications Commission (FCC).
"Protecting consumers from service disruption is our first and highest priority," he added.
Reassurance
Top executives from WorldCom, Global Crossing and Qwest Communications were testifying.
Global Crossing filed for bankruptcy in January with debts of $12.4bn, but said services were continuing as normal.
"The fact of the bankruptcy has not disrupted or affected a single customer," said Global Crossing's chief executive John Legere in a written testimony.
WorldCom filed for the biggest corporate bankruptcy in history earlier this month, but pledged to keep services maintained.
"I can assure this committee that we will continue to work closely with the commission to ensure that customers will not suffer adverse consequences as a result of our current financial status," said WorldCom's chief executive John Sidgmore said in written testimony. said it
Qwest's chief operating officer Afshin Mohebbi gave similar reassurances. On Sunday Qwest admitted that it had made major accounting errors, and was already under investigation by the US Department of Justice and the financial regulator.
Competition fears
Senators also expressed their concern over whether consumers could lose out if the future saw reduced competition in the industry, if companies fail or are taken over.
FCC chief Michael Powell has said previously that he may consider letting one of the regional telephone companies to take over WorldCom.
But in testimony on Tuesday, Mr Powell acknowledged that some mergers could harm consumer choice.
"Regulators will have to walk a fine line to achieve stability, while not squelching competitive opportunity," he said.