one31 (formerly GM M. days) is a television channel, digital high-definition (HDTV), administered by Thirty Limited, a subsidiary of GMM Grammy and Takonkiet Veerawan. It is a director of a GMM Grammy as well as GMM 25.
one31 was first broadcast on December 1, 2011 with the name "1-Sky One" with content that brings various television programs. Both music genres, TV dramas and movies which are produced by companies in GMM Grammy which are in one of the main channels broadcasting on channel 0 of the television service via "One Sky". Later, on 1 April 2012, they changed the service name and the set-top box to "GMM ZAT". The channel name was changed to "GMM Zatitski". Then on November 1, they changed the name again to "GMM One". They also moved it to channel number 7 of GMM and began to signal for free viewing (free-to-air) on May 1 , 2013 as well as adding new content such as dramas, foreign series and entertainment news, including publishing the logo. The slogan of the channel is "Watch every day well" On September 1, Channel One could be watched via GMM ZAT and PSI, which can decode only Biss signals only.
On 1 April 2014, GMM One began to bring the signal up to experiment digital broadcasting system through channel number 31 of the second set of signal transmission equipment of the Royal Thai Army Television Station, in channel 36 for the Bangkok station before changing its name to "Channel 31" which is being currently used since May 1, 2014. Sports matches with high definition images were also being shown in Thailand for the first time.
Later, around August of that year, Channel 31 began offering news programs under the name "One News", in which the first phase had only two parts: "Daily News" and "News Tonight" with the program "Catch Ton Chon Plai" and "One Big World". Later in September, one31 added more morning and midday news programs, as well as adjusting the time of day news coverage from the original 17:00 up to 18:15. In addition, GMM also brought the main news section up every period to broadcast in parallel with before GMM split up to present the news program individually on December 25.
On 13 October 2016 at 7:00 pm, the station announced the Bureau of the Royal Household on His Majesty King Bhumibol Adulyadej had passed away. The NBTC therefore ordered all television stations, including one31, to stop broadcasting normal programs for a period of 30 days and to provide a signal from Royal Thai Army Television Station (TVC), Radio Television Station of Thailand (TAT) together with the Special Television of Thailand (ROR) to publish a documentary of His Majesty's duties, including special content related to him such as films, drama, etc. to air temporarily. After that, all the television channels were being broadcast as normal. The station therefore changed the program schedule to be ad-hoc by abstaining from entertainment programs, adding news programs on Saturdays and Sundays including programs to honor until after 30 days, the station gradually broadcasted regular programs one by one until the normal plan on November 19, 2016.