Fall is usually a busy time of year at eHealth's Sacramento, Calif., call center. The health insurance broker has been in the business of selling individual health insurance online since 1997, and expects the next few months to be very busy, with all Americans now required to obtain health insurance under the Affordable Care Act.
"The more people we can get enrolled, the broader the enrollment is, the more young people we can get enrolled," said CEO Gary Lauer, "the higher the chances for success of this legislation."
At Chicago-based GoHealth, executives this year went on what they describe on their website as a supersonic hiring spree, adding 650 new employees. CEO Clint Jones said he sees the roll out of Obamacare as an opportunity to significantly expand the firm's customer base of 2 million people.
(Read more: 8 things to know about Obamacare)
"We expect on October 1 to have roughly 650-700 licensed benefit advisors, in anticipation for the phones to ring heavily, with all the marketing partners we have in place," he said.
The biggest opportunity for the online brokers came late this summer, when the Obama administration gave them approval to enroll people in subsidized health exchange-based plans on the federally built insurance marketplaces.
After heavy lobbying, a number of online insurance brokers will have access to the plans on the exchanges. Residents in three dozen states, including Arizona, Texas, and Florida, will have the option to sign up for subsidized plans on the private sector's marketplaces.
"For us to be able to tap into the federal data hub and get the data, and allow people to apply subsidies on our site was very powerful," said Jones.
Federal exchange access was an important victory because only plans offered on the government exchanges are eligible for subsidies.
(Read more: How do Obamacare exchanges work?)
The online brokers have not succeeded in gaining access to exchanges in states that have built their own marketplaces, like California, New York and Maryland.
Lazard Capital Markets analyst Steven Halper thinks the states are being protective of the investment they made in developing the exchange infrastructure and jobs involved in operating the marketplaces.
"The upshot is the states have gotten federal grant money from the federal government to develop the exchanges themselves," Halper said, "and they're looking at it as an opportunity to put people to work and develop this capability, and they do not necessarily want participation of the private sector, at least initially."
Side-by-side price comparisons
Halper said it's not clear how many people the brokers will be able to divert from the federal exchanges, but he expects them to see some incremental growth.
The online brokers insist they're not competing with the government exchanges, but point out that they'll be able to offer consumers something the state exchanges will not: a side-by-side comparison of state exchange plans and plans being offered in the private sector.
For those who are at the top range of the income eligibility for subsidies, eHealth's Lauer said an exchange plan may not necessarily offer the best value. That's where the online brokers' call centers, staffed with people experienced with health insurance plans, could make a difference.
"It's going to be our job to help educate people in an unbiased way, so that they can—a consumer can—make a decision that makes the most sense for the individual or their family," he said.
—By Bertha Coombs. Follow her on Twitter: @coombscnbc.