Latest Facebook Messenger 112 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; Android 6.0; HUAWEI VNS-L31 Build/HUAWEIVNS-L31; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/57.0.2987.132 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/112.0.0.17.70;] Android 6 P9 Lite
Mozilla/5.0 (Linux; Android 6.0.1; SM-N920W8 Build/MMB29K; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/57.0.2987.132 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/112.0.0.17.70;] Android 6 Galaxy Note 5
Mozilla/5.0 (Linux; Android 6.0.1; SM-A500FU Build/MMB29M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/55.0.2883.91 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/112.0.0.17.70;] Android 6 Galaxy A5 Duos
Mozilla/5.0 (iPhone; CPU iPhone OS 9_3_3 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Mobile/13G34 [FBAN/MessengerForiOS;FBAV/112.0.0.36.70;FBBV/54364624;FBDV/iPhone7,1;FBMD/iPhone;FBSN/iPhone OS;FBSV/9.3.3;FBSS/3;FBCR/ iOS 9 iPhone 6 Plus
Mozilla/5.0 (iPhone; CPU iPhone OS 9_3_3 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Mobile/13G34 [FBAN/MessengerForiOS;FBAV/112.0.0.36.70;FBBV/54364624;FBDV/iPhone7,1;FBMD/iPhone;FBSN/iPhone OS;FBSV/9.3.3;FBSS/3;FBCR iOS 9 iPhone 6 Plus