Mobile headers for Modify Headers extension: https://addons.mozilla.org/en-us/firefox/addon/modify-headers/ Rename to modififyheaders.json and import.

modifyheaders.json

[{"action":"Modify","name":"User-Agent","value":"Nokia3350/1.0 (05.01)","comment":"Nokia Lowend","enabled":false},{"action":"Modify","name":"Accept","value":"application/vnd.wap.xhtml+xml","comment":""},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3","comment":"IPHONE ios5","enabled":false},{"action":"Modify","name":"User-Agent","value":"NokiaE5-00/SymbianOS/9.1 Series60/3.0 3gpp-gba","comment":"Nokia Featurephone","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (SymbianOS/9.2; U; Series60/3.1 NokiaN95/21.0.016; Profile/MIDP-2.0 Configuration/CLDC-1.1 ) AppleWebKit/413 (KHTML, like Gecko) Safari/413","comment":"N95","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (BlackBerry; U; BlackBerry 9800; en-GB) AppleWebKit/534.1+ (KHTML, like Gecko) Version/6.0.0.141 Mobile Safari/534.1+","comment":"Blackberry","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; LG-LS720 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30","comment":"Android 4.1","enabled":true},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; Android 4.0.3; GT-I9100 Build/IML74K) AppleWebKit/535.19 (KHTML, like Gecko) Chrome/18.0.1025.166 Mobile Safari/535.19","comment":"Android 4.0 - Galaxy S II","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 3.2.1; en-gb; HTC Flyer P510e Build/HTK75C) AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13","comment":"Android 3.2.1","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 3.1; en-us; GT-P7510 Build/HMJ37) AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13","comment":"Android 3.1","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 2.3.5; en-us; LG-P930/V09g Build/GRJ90) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1","comment":"Android 2.3.5","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 2.3.6; en-us; SAMSUNG-SGH-I777 Build/GINGERBREAD) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1","comment":"Android 2.3.6","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 2.3; xx-xx; GT-N7000 Build/GINGERBREAD) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1","comment":"Android 2.3 - Samsung GT-N7000 (Galaxy Note) ","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 2.2; en-us; T-Mobile G2 Build/FRF91) AppleWebKit/533.1(KHTML, like Gecko) Version/4.0 Mobile Safari/533.1","comment":"Android 2.2","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 2.1-update1; en-au; GT-I9000T Build/ECLAIR) AppleWebKit/530.17 (KHTML, like Gecko) Version/4.0 Mobile Safari/530.17","comment":"Android 2.1 - Galaxy S","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 1.5; ru-ru; HTC Hero Build/CUPCAKE) AppleWebKit/528.5+ (KHTML, like Gecko) Version/3.1.2 Mobile Safari/525.20.1=generic_android","comment":"Android 1.5","enabled":false},{"action":"Modify","name":"User-Agent","value":"Mozilla/5.0 (Linux; U; Android 0.5; en-us) AppleWebKit/522+ (KHTML, like Gecko) Safari/419.3=generic_android","comment":"Android 0.5","enabled":false}]