Yealink SIP-T48G Administrator's Manual page 271

Time Zone
GMT+4:30
GMT+5
GMT+5
GMT+5
GMT+5
GMT+5:30
GMT+6
GMT+6
GMT+7
GMT+7
GMT+8
GMT+8
GMT+8
GMT+9
GMT+9
GMT+9:30
GMT+9:30
GMT+10
GMT+10
GMT+10
GMT+10
GMT+10:30
GMT+11
GMT+12
GMT+12:45
GMT+13
Yealink IP phones trust the following CAs by default:
DigiCert High Assurance EV Root CA

Deutsche Telekom AG Root CA-2

Equifax Secure Certificate Authority

Equifax Secure eBusiness CA-1

Equifax Secure Global eBusiness CA-1

GeoTrust Global CA

GeoTrust Global CA2

GeoTrust Primary CA

GeoTrust Primary CA G2 ECC

Time Zone Name
Afghanistan
Kazakhstan(Aqtobe)
Kyrgyzstan(Bishkek)
Pakistan(Islamabad)
Russia(Chelyabinsk)
India(Calcutta)
Kazakhstan(Astana, Almaty)
Russia(Novosibirsk, Omsk)
Russia(Krasnoyarsk)
Thailand(Bangkok)
China(Beijing)
Singapore(Singapore)
Australia(Perth)
Korea(Seoul)
Japan(Tokyo)
Australia(Adelaide)
Australia(Darwin)
Australia(Sydney, Melbourne, Canberra)
Australia(Brisbane)
Australia(Hobart)
Russia(Vladivostok)
Australia(Lord Howe Islands)
New Caledonia(Noumea)
New Zealand(Wellington, Auckland)
New Zealand(Chatham Islands)
Tonga(Nukualofa)
Appendix
259