Besides helping victims of kidnappings or home invasions, 911 texting would be useful for people who are deaf, mute, or experiencing a speech-disabling issue such as a stroke.
The dispatchers will be able to respond, ask questions, and converse via text message. But in most instances, officials say, calling 911 would still be faster and more precise.
In January, the Federal Communications Commission recommended that all counties and cellphone providers enable 911 texting. A scattering of counties have jumped on board, but so far, Indiana is the only state with widespread access.
In May, Verizon, Sprint, AT&T, and T-Mobile agreed to provide the service to customers nationwide.
In Pennsylvania, Allegheny, Dauphin, Franklin, Lancaster, and Luzerne Counties and the City of Allentown can receive texts, according to an FCC list. A spokeswoman for Allegheny County said dispatchers have handled 110 emergency reports via text message since the program launched in May.
The expansion highlights a legislative problem that county officials have been decrying for years: Funding for 911 systems comes from a landline-access fee. But fewer people have landlines, and more calls are coming from cellphones, which pay no fees.
That leaves counties to pick up more of the tab. Last year, for example, Montgomery County paid more than 59 percent of the $11 million cost of its 911 system.
The Pennsylvania Emergency Management Agency is providing a grant to get the system running in Montgomery, Berks, Bucks, and Chester. After that, the counties will again pick up the bill.