• by David Goetzl  @dgoetzl, October 26, 2009

About one-quarter of customers eligible for Verizon's telco TV service have signed up -- helping to drive the number of subscribers higher in the third quarter, although the growth rate slowed.

The company -- the eighth-largest MSO -- added 191,000 net new FiOS TV subscribers, bringing its total to 2.7 million.

The penetration rate is at 24.9% with 10.9 million potential customers -- a figure that was at 19.7% at the end of the third quarter a year ago.

Still, new customer acquisition was slower than in the previous two quarters, and gross sales were lower due to what the company hinted was a slowdown in marketing.

CFO John Killian, speaking on a call to discuss third-quarter results, said FiOS "continues to have good momentum in the market."

AT&T -- which has telco TV service U-verse -- recently said it added a net gain of 240,000 new customers in the third quarter, closing with 1.8 million homes served. But its penetration rate was at a lower 12%.

Verizon also added 198,000 net new FiOS Internet subscribers in the third quarter, and now has 3.3 million customers. Penetration is at 28.5%.

Verizon believes it can continue to add about 1 million new FiOS customers a year, Killian said. FiOS revenue in 3Q was $1.4 billion, up 56% versus a year ago.

One benefit of FiOS, Killian said, is that it can lower cost structure at the company.