Approximately, 33% of Global LTE 4G Services Deployment is on 1800MHz Spectrum Band. Here is a list of operators who have done so

Movicel Angola LTE1800
Optus Australia LTE1800
Telstra Australia LTE1800
Azercell Azerbaijan LTE1800
T-Hrvatski Croatia LTE1800
VIPNet Croatia LTE1800
O2 CzechRepublic LTE1800
Telia Denmark LTE1800
Orange Dominicana in Dominican Republic LTE1800
DNA Finland LTE1800/2600
Elisa Finland LTE1800/2600
TeliaSonera in Finland LTE1800
Deutsche Germany Telekom LTE1800
CSL Hong Kong Limited LTE1800/2600
SmarTone Hong Kong LTE1800
T-Mobile Hungary LTE1800
Telenor Hungary LTE1800
eMobile Japan Band 7 (within LTE1800)
LMT Latvia LTE1800
Omnitel Lithuania LTE1800
Orange Mauritius LTE1800
MTC Namibia LTE1800
Smart in Philippines LTE1800/2600
CenterNet / Mobyland in Poland LTE1800
Optimus Portugal LTE800/1800/2600
Zain Saudi Arabia LTE1800
M1 Singapore LTE1800/2600
SingTel Singapore LTE1800/2600
Si.mobil Slovenia LTE1800
KT South Korea LTE1800
Du UAE LTE1800
Etisalat UAE LTE1800/2600

Videocon in India is also planning to launch LTE 1800 Operations [Update 06-12-2012]