Do you know what the two Ms in DZMM stand for?

DZMM is celebrating its 30th year in news and public service. Here are 30 things you may not know about ABS-CBN's flagship AM radio station:

1. Fidela "Tiya Dely" Magpayo was the first anchor to grace the airwaves of the station, with her program "Dear Tiya Dely," which aired at around 3 p.m. on July 22, 1986.

2. In addition to "Kabayan" Noli De Castro, DZMM pioneers included late broadcast icons Ernie "Ka Ernie” Baron and Cesar "Kuya Cesar" Lacbu Nucum.

3. The "MM" in DZMM stands for "Malayang Mamamayan (Free Citizen)".

4. DZMM was formerly known as "Himpilan ng Malayang Mamamayan" and was later re-launched as DZMM Radyo Patrol 630 (sais-trenta).

5. DZMM's hotline number is 416-6300. This corresponds to the frequency the station uses for its broadcasts, which is 630kHz.

6. Back in the day, production assistants had to be next to the anchor on board.

7. In 1996, DZMM became the first AM station in the Philippines to stream over the Internet. A link to the radio’s feed was included in the ABS-CBN news website.

8. In 1998, ABS-CBN launched Sky Patrol, the country's first news chopper. It changed the way news was gathered and delivered. Radyo Patrol reporter Ricky Velasco was the main anchor for DZMM’s Sky Patrol. He was joined by other reporters for the Sarimanok News Network (later renamed ABS-CBN News Channel) and ABS-CBN Channel 2.

9. DZMM launched TxtPatrol in 2001, amid the rising popularity of mobile phones and text messaging. By keying in DZMM (SPACE) REACT (SPACE) NAME and MESSAGE, then sending the text message to 2366, the public can submit their reactions, questions and requests for greetings. However, TxtPatrol's most significant role was—and continues to be—to serve as a venue for the public to report their situation and ask for aid during disasters and emergency situations.

10. With the launch of DZMM TeleRadyo in 2007, DZMM took its programming to a new level. TeleRadyo was made available for TV via SKYcable channel 22, and The Filipino Channel (TFC). With its datascreen format, DZMM Teleradyo enabled the inclusion of more elements such as news headlines, public service announcements, weather bulletins and other graphics.

11. DZMM TeleRadyo was the first to use mobile phone videos and 3G wireless internet technology to deliver news during the 2007 Glorietta blast.

12. In 2008, DZMM launched its website www.dzmm.com.ph. This was recently integrated with the official website of ABS-CBN, and can now be found at http://news.abs-cbn.com/dzmm/home.

13. DZMM's official slogan is, "Una sa Balita, Una sa Public Service (First in News, First in Public Service)."

14. Before being housed at the ABS-CBN main building in Quezon City, DZMM's radio studio used to be located at Benpres Building in Ortigas.

15. DZMM is fueled by stories from its Radyo Patrol reporters or RPs. New reporters are usually called RPs until they earn their official call signs.

16. The legacy of a call sign, or the number attached to a Radyo Patrol reporter, is considered a rite of passage. A number is a kind of nickname for each RP, and a badge of honor which means they are a full-fledged Radyo Patrol reporter.

17. Radyo Patrol reporters keep their numbers for life. The most recent RPs to receive call signs were RP48 Zandro Ochona, and RP49 Zhander Cayabyab.

18. RP3 Vic "Tres" de Leon Lima is currently the most senior Radio Patrol reporter doing active board work. He goes on air for newscast "Radyo Patrol Balita alas Kwatro" and commentary program "Pasada Sais Trenta" with Karen Davila.

19. Some notable RPs-turned-TV personalities include "Umagang Kay Ganda" hosts RP27 Jorge Carino and RP28 Anthony "Ka Tunying" Taberna.

20. While the job of radio field reporter usually attracts men, there are also female RPs including RP16 Ruby Tayag, and new blood Angel Movido and Raya Capulong.

21. Aside from SKYcable channel 22, and The Filipino Channel (TFC), DZMM TeleRadyo can also be viewed via ABS-CBN TVplus. Prior to the official launch of the TVplus for nationwide sale, DZMM gave away free units of the "Mahiwagang Black Box" to lucky viewers and listeners.

22. DZMM's public service efforts go way back to 1987, when the station launched its first free medical and dental mission for over 200 people in need.

23. One of its longest-running shows and core programs is "Aksyon Ngayon," which is dedicated to public service. It is anchored by Julius Babao, Kaye Dacer, and Zaldy Naguit.

24. DZMM stages year-round public service events, like the "Red Alert Expo," "Teaching Learning Caring" programs, and the "Buntis Congress."

25. Peter Musngi, famously known as the "golden voice of ABS-CBN," once led DZMM as its station manager. He spearheaded numerous projects and led Manila Radio Division and ABS-CBN Sports to success. He now co-anchors "Teka Muna" with Pat P. Daza.

26. The voice behind many DZMM radio commercials belongs to May Valle Ceniza. She started voicing time checks in 1995, and is also currently DZMM’s special projects head and anchor of "Magpayo nga Kayo."

27. DZMM is open 24 hours a day, 365 days a year. That means operational employees have to show up for work during disasters and holidays, including Christmas Day and New Year's Eve. The station signs off briefly every Sunday at 10 p.m., but signs on again at 4 a.m. on Monday.

28. The only time DZMM goes completely off air is during Holy Week. The station halts its programming at midnight of Maundy Thursday and goes back on air at 4 a.m. on Easter Sunday. But even so, some employees come in to do annual maintenance work. Other employees are also listed as first responders and are required to come in should there be a need to break important stories.

29. Every year, DZMM releases a new rendition of its station ID. Some artists who have lent their voices include Piolo Pascual, Lani Misalucha, Arnel Pineda, and Teddy Corpuz.

30. DZMM's current station manager Marah Capuyan is the first female boss to head the radio network. She started as a production assistant, rose from the ranks, and now leads the station in maintaining its position as the number one AM radio station in Metro and Mega Manila.

Find out more about the legacy of DZMM by watching a documentary special titled “Trenta, Sais Trenta: Kwento ng DZMM" that will be aired on October 9, 2016 on ABS-CBN's "Sunday's Best" and re-aired on October 10 and 15, 2016 on DZMM and DZMM Teleradyo.