DEAR ABBY: I am speaking on behalf of police dispatchers who respond to 911 calls.

So many people are not clear about when to call 911. In a nutshell, they should call only when there is an immediate threat to human life or property.Do not call because a dog is barking and you can't sleep.

Do not call if your cat is in a tree and you can't get it down.

Do not call if it is getting dark and your 11-year-old son is not home from school and there is no football practice that night.

Do not call if you notice sparks coming out of your television. If you smell something burning in either the apartment above you, below you, on either side of you (but you are sure it's not in your apartment), do not call 911. Call the Fire Department!

If you are witnessing a crime - CALL IMMEDIATELY. If you wait 20 minutes to call because you were on your way home when you saw it happen, we probably won't be able to do anything except take a report. If you had called immediately, we might have been able to catch the bad guy.

Also, when you call 911, expect to answer some questions. They are important or we wouldn't ask them. Callers think all they have to do is say, "Send police," and we will rush over. Unfortunately, that is not the case. Only on TV do they get a call and send the police out in five seconds. Also, we could get a patrol car out faster if the caller would stop cussing, yelling and insulting us.

We try to be professional, courteous and fast, but the abuse we get is unbelievable.

We dispatchers work various shifts. The lines are staffed around the clock, and somebody has to work weekends and holidays, so we all take our turns.

Nobody is a dispatcher because it pays well. It doesn't when you consider the hours and stress involved. It takes a very caring person to do the kind of work we do. Please give us a break!

Thanks, Abby, for printing this. I've seen everything from soup to nuts in your column, so this should make it. Just sign this . . . "911"

DEAR ABBY: Last year, my son and his wife - I'll call them Tim and Barbara - divorced after 12 years of a rocky marriage. They have two beautiful daughters, 12 and 8. I love these children with all my heart. It was a messy divorce and created a lot of hard feelings.

Three weeks after their last separation, Tim learned that Barbara was pregnant. He says it must be another man's child. (Barbara slept around a lot.)

Now for the shocker. I just received an invitation to a baby shower for Barbara. Can you believe it? I don't intend to acknowledge her child as my grandchild with all these doubts about whether it's my son's or not. Also, I plan to distance myself from Barbara. I'm sure she's expecting Christmas pres-ents, too.

How would you handle this? Barbara lives 190 miles from me. - GRANDMOTHER IN QUESTION

DEAR GRANDMOTHER: Regardless of how you feel about Barbara, her children will always be your grandchildren. So unless you want to write them off along with their mother, don't be so quick to distance yourself from Barbara.

If I were you, I would send a gift to the baby shower.

Most teenagers do not know the facts about drugs, AIDS and how to prevent unwanted pregnancy. It's all in Abby's updated, expanded booklet, "What Every Teen Should Know." To order, send a business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Teen Booklet, P.O. Box 447, Mount Morris, IL 61054. (Postage is included.)