I can't get the text message with extension number.

According to your description, I suggest you try the following methods: Settings-Application Manager-Slide Screen Options (All)-Find Information-Click Enter to try to clear the data. Try to replace another SIM card. Check whether the mobile phone is equipped with security guards or third-party SMS software, and test it after unloading. Back up mobile phone data (phone book, SMS, multimedia files, etc.). ) and restore the factory settings. If the above method still fails, please send the equipment to Samsung Service Center, and the engineer will check the machine and deal with it.

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1, dual-card dual standby mobile phone refers to a mobile phone, which can hold two SIM cards at the same time, and both cards are in standby state. Dual-card dual standby in the market generally refers to dual-card dual standby of the same network standard, that is, GSM network dual-card dual standby, CDMA network dual-card dual standby, PHS network dual-card dual standby; Dual card dual standby mainly refers to the first case, namely GSM dual card dual standby.

2. Dual-network dual standby is the combination of GSM network and CDMA network. A mobile phone can be plugged into two number cards of different networks at the same time and turned on at the same time. Users can dial, send and receive short messages at will without switching networks, and they can use 3G/4G to surf the Internet anytime and anywhere, so that business people can enjoy the freedom of mobile office and the fun of rest and entertainment. Some "dual standby" in the market are not real dual card dual standby. For example, some mobile phones can insert two cards, but only put two cards into the phone, which is just "dual card standby". It is necessary to switch from A card to B card (or from B card to A card) through mobile phone switching, so as to realize pseudo-dual card standby.