Cannot connect with 3g modem during Arch installation

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http://unix.stackexchange.com – I was trying to install Arch Linux with 3g modem. Previously downloaded usb_modswitch and wvdial and their dependencies. Booted acrh and installed them. Then copied my ubuntu's /etc/wvdial.conf in arch. Then I connect with wvdial and it says connected, modem indicator also says connected. But it is actually not! ping www.google.com says unknown host! The modem is HUAWEI E1550 (From a provider in Bangladesh). (HowTos)