Please confirm the following before roaming abroad: 1. Has China Telecom opened CDMA or GSM international roaming service with the operators going to the countries or regions? 2. Whether the mobile phone number has applied for "international roaming" and "international long distance" services. 3. Do I need to change my mobile phone in the country or region I am going to? (1) At present, the frequency of CDMA network in parts of the United States and Canada is 1900Mhz, while the frequency of CDMA mobile phones in China is generally 800Mhz. If roaming in the United States and Canada with CDMA system, you need to use a CDMA mobile phone that supports both 800Mhz and 1900Mhz. (2) Some GSM operator networks in North America and South America use the frequency of 1900Mhz, while domestic GSM mobile phones generally only support the frequencies of 900Mhz and 1800Mhz. If you roam in North America and South America of GSM system, you need to change the mobile phone that also supports GSM1900/CDMA1900/WCDMA. (3) If you roam Japan and South Korea through CtoG, you need to replace Tianyi International Card to cooperate with WCDMA mobile phone. 4. Is there a CDMA network coverage restriction in the country or region you are going to? Hong Kong: At present, it covers commercial centers such as Kowloon, Victoria Bay, Rome, Luohu and Disney. Taiwan Province province: weak coverage in mountainous areas and seaside; Israel: The main areas covered are Jerusalem, Haifa, Tel Aviv, Beersheba and Akka; Bangladesh: excluding the arms control zone; Indonesia: only Java is covered (Bali is not covered); Note: If the above countries or regions need to roam the whole country, they can change Tianyi International Card and bring GSM mobile phone before leaving the country. 5. Countries without SMS sending function under 5.CDMA network (SMS can be received) 6. China Telecom Tianyi International Card users can use dual-mode mobile phones for international roaming. If there are GSM and CDMA networks in your country or region, you can choose to switch between GSM and CDMA networks to realize roaming between different networks. In order to provide the best roaming communication guarantee for overseas travel, if the back of UIM card is not marked with Tianyi International Card (new) or Tianyi UIM card, please go to the business hall to replace the new card. 7. As setting call forwarding may affect the normal roaming service (such as unable to log on to the network), or may lead to two-way international calls, resulting in unnecessary telephone charges disputes, please cancel the call forwarding setting before roaming abroad to avoid the high fees that may be generated by call forwarding. International roaming call transfer fee standard 8. Some functions of services such as communication assistant and mobile phone secretary are similar to call transfer. International roaming customers are advised to choose this kind of service carefully, and please cancel it before roaming abroad to avoid possible high call transfer fees. 9. For users going to South Korea, please note that due to the network reasons of Korean operators, a small number of users cannot use the CDMA roaming service in South Korea. Please call 10000 before going abroad or go to the business hall to verify whether this number can be used normally. If in doubt, you can apply for a new card free of charge in the business hall. 10, 3G smart phones may also generate a large amount of data in standby state, such as customized mobile phone newspaper, download function of mobile phone newspaper, download function of navigation electronic map, automatic update of software and push function of e-mail, especially e-mail with large attachments. These emails may often be several megabytes, which will generate a lot of traffic, which is generated without the customer's feeling. Therefore, it is recommended to turn off the international roaming function of data before leaving the country. Click on "official website" Customer Service 2 17 below for more service offers.