Cell phone and landline customers experienced connection problems after Tuesday's earthquake, but there were no immediate reports of trouble for police and rescue workers.
Verizon Wireless, AT&T, Sprint and T-Mobile did not immediately report infrastructure damage, although representatives said their networks were congested as the quake sent people scrambling for their phones.
"There were tremors, and everyone decided to call and say, `Did you feel it?'" Verizon Wireless spokesman Tom Pica said.
The congestion was reminiscent, on a much smaller scale, to the frenzy that clogged cellular networks after the Sept. 11, 2001, terrorist attacks.
Police and rescue workers now have priority phones that can get through even when there's a flurry of calls.
Still, the Federal Emergency Management Agency asked people to use text messaging or email for a few hours after the Tuesday quake to keep lines open for emergency responders.
Sprint said some customers might be experiencing delays, but spokesman John Taylor said the company had received no reports of problems from emergency personnel. A District of Columbia police spokesman said officers did not have problems responding to calls.
Pica said there was no damage to the Verizon's equipment. He said the crush of phone calls made it hard for some customers to get through for about 20 minutes after the quake, but he said the congestion appeared to be clearing later in the afternoon.
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