The children of the District of Columbia have a new friend. The D.C. Hotline has added to its services "PhoneFriend," an after-school telephone number for children -- particularly those left at home alone -- to call when they need to talk to an adult.

"It's targeted to elementary age children, to provide information if they run into a problem and can't get in touch with their parents," said Julie Estes, an administrator for D.C. Hotline, the 10-year-old telephone counseling and referral network. "It's a place for them to reach out to when they're lonely.

A phone pal for children is particularly welcomed in the District, which has the highest proportion of working mothers in the country, said Estes. But no one is sure of just how many kids are left alone after school

"We had to estimate the number . . . because most parents don't like to talk about it," she said. "We've been told from conversations with students, it is estimated that 13 percent of the grade school population comes home to an empty house."

As for why a child might need PhoneFriend, Estes said, "They might need to call if a pet gets away and they don't know what to do, or to ask where to put their rain-soaked clothes."

From similar programs around the country, the volunteers and staff at Hotline have learned that they probably will spend most of their time being phone buddies to today's "latchkey" children, kids who stay at home alone after school until the adults come home from work.

"Most calls come from kids who are lonely and bored," said Estes, repeating information passed on to her from people involved in programs similar to PhoneFriend.

Both Montgomery County and Prince George's County have phone lines for kids. The Prince George's County Mental Health Association runs Care Line, a year-old after-school helpline for children, which is in service from 2 p.m. to 9 p.m.

The Prince George's group also provides a service in which volunteers make daily calls to registered children to make sure they got home from school okay.

"Most kids who call don't really like being by themselves and they want to chit-chat," said Ronnie O'Branovich, director of the latchkey programs at the PG Hotline. "Our average caller is 8 or 9 years old.

"Our first call was from a little girl who was very frightened about being left by herself," O'Branovich recalled. "She lived in a rural area. She called more than once and sometimes she got hysterical. Finally, we called her mother and advocated she arrange some other kind of day care.

"Eventually, the mother moved so the little girl would be closer to school and she would be closer to her job," she said. "In the interim she made arrangements for the child to go to someone else's house. I think it demonstrated to us the kind of thing we could do."

The area's only 24-hour help line for children is the Oak Leaf After School Line in Montgomery County. While the service receives the same kinds of calls as the Prince George's line, Cindy Lehman, a counselor, said, "If there's a storm or if children are afraid, they'll call.

"We had an unusual call today," Lehman said recently. "A girl found a baby bird and got it down from the tree and wanted to know what to do. We were going to call the animal shelter, but then we decided to have her wait until her mother came home and tell her to call the shelter."

In the District PhoneFriend will be promoted through flyers and phone stickers passed out at schools and PTA meetings. Initially, PhoneFriend lines will operate from 3 p.m. to 7 p.m. school days, but Estes said the agency hopes to expand to seven days a week.

*Children can call "PhoneFriend" Monday through Friday from 3 p.m. to 7 p.m. at 223-2244.

*The number for Care Line in Prince George's county is 552-2273. Children can call between 2 p.m. and 9 p.m.

*The Oak Leaf After School Line in Montgomery County can be called anytime at 986-8886.