Model A1524 iphone6 plus Unlocked not working on China Telecom

i have iphone6plus model A1524 , but it dont support china telecom carrier . when i put my carrier than it start work but after few seconds the signals dissappear and than no service . i checked on china telecom website they say that this model support china telecom and i seen here too many chinese peoples using this model they buy here in china but i buy in my country , only this difference other all things are same . so i dont know whats the problem is ? when i go to apple store they told me that the phone is good and when i go to carrier they told me that our sim card is good . i dont know how to solve my problem .

please any suggestion ??