* AT&T, T-Mobile USA sign wireless roaming agreement
* Sprint, AT&T say making progress in network improvements
* Verizon Wireless offers free phone charging
* AT&T extends payment window
NEW YORK/WASHINGTON, Oct 31 (Reuters) - Telecommunications companies said they were working to restore services on Wednesday after floods and power outages from Hurricane Sandy affected mobile phones, Internet, home phones and cable television in the U.S. Northeast.
Rivals AT&T Inc and T-Mobile USA said they agreed to open their networks to each other's customers in New York and New Jersey to help their coverage as a result of the storm.
Verizon Communications Inc said it was still focusing on restoring landline services below 39th Street in Manhattan, where it said ``conditions are bleak.''
The New York-based company, which suffered flooding in three central offices that hold key telecom equipment, said it spent the last day pumping water out of buildings and bringing in portable generators.
Flooded basements had damaged some generators and fuel pumps, Verizon said, but voice switches and data equipment located on higher floors were not damaged.
Sprint Nextel Inc, the No. 3 U.S. wireless provider, and AT&T, the No. 2 wireless service, said they were making progress in improving their wireless services.
The number of wireless broadcast towers that are out of service in Sprint's network is declining, spokeswoman Crystal Davis said.
``We are getting the sites back up and running. We are working aggressively,'' Davis said, adding that it was too soon to release numbers. The company said workers are unable to access cell sites in some flooded areas.
FLOODING, POWER LOSS, DEBRIS
AT&T said it could not say to what extent the pact with Deutsche Telekom's T-Mobile USA would improve its coverage.
``The vast majority of our cell sites in the Northeast are online and working,'' AT&T spokesman Mark Siegel said, but the company is still having issues.
``Flooding, power loss, transportation and debris all pose challenges'' in areas that were hard-hit in New York City and New Jersey, he said.
AT&T said it would extend its late-payment window for wireless and wireline customers in the storm region who are behind. It will also waive late payment fees and will not disconnect services because of late payments.
Verizon Wireless, a venture of Verizon and Vodafone Group Plc, said more than 94 percent of its cell towers between Maine and Virginia were up and running. It is still working to restore services at sites that are offline in New York City and northern New Jersey.
``As power and connectivity conditions have improved over the last 24 hours, we have seen some improvement to wireless service in Lower Manhattan and elsewhere in the metropolitan area,'' Verizon Wireless said.
Verizon Wireless and Sprint use the same network technology. Neither company had any immediate comment on whether they have had any discussions about forging an agreement similar to the network roaming agreement forged by AT&T and T-Mobile USA.
NO POWER TO CHARGE PHONES
Along with spotty coverage many people in New York City were having trouble finding a power source to charge their phones because of electricity outages in large portions of the city's five boroughs.
Verizon Wireless said it is offering free cellphone charging to customers of any operator at its stores in the hurricane region. It is working on delivering mobile charging stations to hard-hit areas such as New York City.
The Federal Communications Commission said on Tuesday that about 25 percent of cell sites were out of service, and it warned that wireless service could worsen before improving due to power outages.
On Wednesday afternoon, FCC Chairman Julius Genachowski said conditions were improving but that ``serious outages remain, particularly in New York, New Jersey and other hard-hit areas.''
The regulator said there were still some problems with emergency calls that it had referenced on Tuesday.
Some emergency 911 calls were still being re-routed to other 911 call centers, and were arriving without data showing police or firefighters the caller's location, David Turetsky, the head of the FCC's Public Safety and Homeland Security Bureau, said in a call with reporters.
CABLE SERVICES DISRUPTED
Cable operators Cablevision Systems Corp, Comcast Corp and Time Warner Cable also were having service problems.
Time Warner Cable said it has had no reports of significant damage to its network, but it is hard to assess the situation because many of its customers have no power.
It said it has crews ready to go to affected neighborhoods once power has been restored to examine any local damage and begin repairs.
Cablevision, which had been due to report earnings Nov. 1, said on Wednesday that it rescheduled the release to Nov. 6. On Tuesday, Cablevision said it faced widespread service interruptions primarily related to loss of power and said it was working on service restoration.
Canaccord Genuity analyst Tom Eagan expects Cablevision to incur ``significant storm-related costs'' in the current quarter. The company had booked $20 million of costs related to Hurricane Irene, which hit the U.S. Northeast in 2011, Eagan said in a research note.
Comcast, whose headquarters is in Philadelphia and serves East Coast states, said it had nothing new to report on Wednesday. It said on Tuesday that service should be restored as power comes back.