The phone number to save your marriage: (02) 640-4343 or 1-877-963-8938 toll-free from abroad.

Save these phone numbers. They might save your marriage.

The phone numbers have changed, but the message is identical to the one I wrote in this column nearly two decades ago.

Back then, the number The Jerusalem Post Magazine publicized was the home phone of the first woman certified as a yo'etzet, an expert consultant on following the religious rules that govern a married couple's intimate life. Tens of calls turned into hundreds. Who knew?

The avalanche of phone calls that followed threatened to derail the newly minted consultant's own marriage, jests Rabbanit Chana Henkin, founder of Nishmat, the Jeanie Schottenstein Center for Advanced Torah Study for Women. She stepped in to rescue the besieged consultant – and what was to become the Golda Koschitzky Women's Halachic Hotline was born.

I'm surprised and gratified for the recognition of that old column, but humbled by the women who have without fanfare answered close to 400,000 phone calls since then.

The hotline has become a vital resource for Jewish families. The younger callers don't remember a time when women could direct their excruciatingly embarrassing and detailed private religious questions about menstruation, childbirth and fertility only to a rabbi.

Henkin is tracing the history of the hotline at a preperformance reception of Mikva the Musical, Music and Monologues from the Deep, a show that I've previously reviewed in these pages. Fittingly, the performance is a fund-raiser for the hotline's free services.

A mikveh is a dedicated pool of water in which women immerse to return to a state of ritual purity. The most common hotline questions still involve whether or when a woman can immerse, a question that requires considerable expertise in Jewish law.

AMERICAN-BORN HENKIN was living with her husband, Rabbi Yehuda Henkin, in Beit She'an when she discovered that few local women were using the local mikveh, which was locked on Friday nights for the attendant's convenience.

Henkin's personal style rejects crashing through locked doors. She's more comfortable in quietly and effectively removing barriers. She recruited the local rabbi's wife and a respected woman in the Moroccan community to form a panel with her to teach and make beloved Judaism's laws of family purity. She found the mikveh attendant a different job. The use of the mikveh quadrupled.

After moving to Jerusalem and establishing Nishmat, Rabbanit Henkin realized that despite the imperative to ask for rabbinical advice, few women, no matter their piety, wanted to discuss aberrant excretions with their rabbis. Instead, they often unnecessarily postponed going to the mikveh for days, weeks or even months, for fear of violating religious law. A friend of Rabbanit Henkin confided that because of premenopausal changes, her marriage was in trouble. The friend couldn't bring herself to discuss her irregular period with the rabbi, and sent questions via her husband. If only she could discuss her issues with a woman expert!

With the encouragement of her own husband, Henkin opened the Keren Ariel Women's Halachic Institute at Nishmat in 1997 to train the first yo'atzot, expert consultants.

HOTLINE PHONE CALLS these days – some 40 an evening – go way beyond technical questions. At the preperformance discussion, a veteran consultant who has been fielding phone calls for 15 years describes a recent call from a bride panicking before the wedding, certain that she would abhor the mikveh and sex life. Another caller says she wants to know if she can go to the mikveh with radiation set-up marks, but really doesn't want the attendant to know she's battling cancer.

There are questions from gay women couples who want to incorporate family purity into their lives. There are the callers who suffer from abuse and those with obsessive-compulsive syndrome. Any new information or misinformation promulgated on social media about birth control brings a torrent of inquiries.

The veteran consultant recently had to guide a woman in India who wanted to immerse in the Ganges. Saturday night calls typically include inquiries from Australia, where the Sabbath is over.

The consultants work three-hour shifts, so they are able to stay alert.

Nishmat has added a course with the Keren Gefen mind-body fertility center to better guide fertility-challenged women.

In a fascinating turnaround, rabbis, too frequently avail themselves of the hotline for information, and frequently make use of the consultants' thorough and updated, comprehensive website (www.yoatzot.org).

The backbone of the service remains the dedicated consultants. Candidates, says mentor Henkin, need "an unswerving religious commitment, with a strong education in Judaism and a lively, empathetic personality."

The two-year study program covers complex halachic issues from primary sources, anatomy, women's medicine and counseling skills. There's a notoriously tough exam. Consultants receive ongoing updates from physicians, but don't give medical advice per se. In-house rabbis are consulted when a consultant is unsure of a halachic ruling. A new consultant will likely call one of the Hotline's rabbis every evening; a veteran consultant calls far less. More than a 110 consultants have been certified.

RABBANIT HENKIN has continued her work despite her personal tragedy: terrorists murdered her son and daughter-in-law, Rabbi Eitam Shimon and Naama Henkin in front of their children in 2015.

"I hope my work will serve as a spiritual elevation for their souls," she says.

And how can I not mention that the "veteran counselor" quoted above is Rachelle Sprecher Fraenkel, the mother of Naftali Fraenkel, one of the three teenagers kidnapped and murdered in 2014. In constant demand to teach and inspire, she has gone on answering tens of thousands of questions. "Many of the answers are short, but I've sometimes spent 45 minutes on the line with someone and know I've made a big difference in her life."

All the counselors say that, not infrequently, a woman will call to say: "You don't know me, but nine months ago you helped me become pregnant, and I wanted to tell you that my baby was just born."

In addition to the phone numbers above, Fraenkel often finds herself giving callers her personal cellphone number. No, we're not publishing it here.