for ZTE USB MODEM, u need to disable the auto run first before plug into router, otherwise the router wont recognize your modem.
to disable the auto run:
plug in your zte modem in pc/laptop -> open command prompt-> type in AT+ZCDRUN=8 (Disable cd /flashdrive autorun ) -> enter -> done
then plug it into the router and u are ready to go,.
AT commands
Command Description
ATI Returns modem information
AT+COPS=? Returns the list of operators present in the network
AT+ZCDRUN=8 Disable cd (flashdrive) autorun
AT+ZCDRUN=9 Enable cd (flashdrive) autorun
AT+ZBANDI=0 Automatic band selection (default)
AT+ZBANDI=1 UMTS 850 + GSM 900/1800
AT+ZBANDI=2 UMTS 2100 + GSM 900/1800 (Europe)
AT+ZBANDI=3 UMTS 850/2100 + GSM 900/1800
AT+ZBANDI=4 UMTS 850/1900 + GSM 850/1900
AT+ZBANDI? Report band selection mode
AT+ZSNT=0,0,0 AUTOMATIC network selection, GSM+WCDMA
AT+ZSNT=0,0,1 AUTOMATIC network selection, GSM+WCDMA,GSM preferred
AT+ZSNT=0,0,2 AUTOMATIC network selection, GSM+WCDMA,WCDMA preferred
AT+ZSNT=1,0,0 AUTOMATIC network selection, GSM only
AT+ZSNT=2,0,0 AUTOMATIC network selection, WCDMA only
AT+ZSNT? Returns network selection mode
Another thing is the ZTE MF668 and other modems support both UMTS 900 and 2100. If the carrier is available in both then it will lead to problems and slow up the dail up considerably or even slow down the router dialing process,..