plug the modem.
Then open a terminal and type
dmesg
and post the out put.
lachitha@lachitha-desktop:~$ lsusb
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 05c6:0018 Qualcomm, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
lachitha@lachitha-desktop:~$
this is dmesg display
[UTC (1300688935)
[ 0.534892] BIOS EDD facility v0.16 2004-Jun-25, 0 devices found
[ 0.534896] EDD information not available.
[ 0.545542] input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input3
[ 0.567486] ata1.00: HPA unlocked: 80291135 -> 80293248, native 80293248
[ 0.567507] ata1.00: ATA-7: Maxtor 6E040L0, NAR61HA0, max UDMA/133
[ 0.567514] ata1.00: 80293248 sectors, multi 16: LBA
[ 0.567583] ata1.01: ATAPI: DVD-ROM DDU1632, VER AS19, max UDMA/33
[ 0.567628] ata1.00: limited to UDMA/33 due to 40-wire cable
[ 0.623764] ata1.00: configured for UDMA/33
[ 0.640120] ata1.01: configured for UDMA/33
[ 0.963458] isapnp: No Plug & Play device found
[ 0.963895] scsi 0:0:0:0: Direct-Access ATA Maxtor 6E040L0 NAR6 PQ: 0 ANSI: 5
[ 0.964344] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 0.965701] scsi 0:0:1:0: CD-ROM SONY DVD-ROM DDU1632 AS19 PQ: 0 ANSI: 5
[ 0.972773] sr0: scsi3-mmc drive: 4x/40x cd/rw xa/form2 cdda tray
[ 0.972788] Uniform CD-ROM driver Revision: 3.20
[ 0.973144] sr 0:0:1:0: Attached scsi CD-ROM sr0
[ 0.973325] sr 0:0:1:0: Attached scsi generic sg1 type 5
[ 0.973781] sd 0:0:0:0: [sda] 80293248 512-byte logical blocks: (41.1 GB/38.2 GiB)
[ 0.973918] sd 0:0:0:0: [sda] Write Protect is off
[ 0.973925] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[ 0.973995] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 0.974359] sda: sda1 sda2 < sda5 sda6 sda7 sda8 >
[ 1.028831] sd 0:0:0:0: [sda] Attached SCSI disk
[ 1.079782] Freeing initrd memory: 7781k freed
[ 1.152318] ata2.00: ATAPI: HL-DT-ST RW/DVD GCC-4522B, 1.03, max UDMA/33
[ 1.184312] ata2.00: configured for UDMA/33
[ 1.185842] scsi 1:0:0:0: CD-ROM HL-DT-ST RW/DVD GCC-4522B 1.03 PQ: 0 ANSI: 5
[ 1.188187] sr1: scsi3-mmc drive: 52x/52x writer cd/rw xa/form2 cdda tray
[ 1.188511] sr 1:0:0:0: Attached scsi CD-ROM sr1
[ 1.188672] sr 1:0:0:0: Attached scsi generic sg2 type 5
[ 1.188802] Freeing unused kernel memory: 660k freed
[ 1.190682] Write protecting the kernel text: 4680k
[ 1.190748] Write protecting the kernel read-only data: 1844k
[ 1.251375] udev: starting version 151
[ 1.800491] FDC 0 is a post-1991 82077
[ 1.816228] sis900.c: v1.08.10 Apr. 2 2006
[ 1.816360] alloc irq_desc for 19 on node -1
[ 1.816366] alloc kstat_irqs on node -1
[ 1.816387] sis900 0000:00:04.0: PCI INT A -> GSI 19 (level, low) -> IRQ 19
[ 1.817557] 0000:00:04.0: Realtek RTL8201 PHY transceiver found at address 1.
[ 1.829473] 0000:00:04.0: Using transceiver found at address 1 as default
[ 1.839623] eth0: SiS 900 PCI Fast Ethernet at 0xe400, IRQ 19, 00:2a:43:00:6e:f5
[ 2.363066] EXT4-fs (sda1): mounted filesystem with ordered data mode
[ 13.703721] Adding 566264k swap on /dev/sda8. Priority:-1 extents:1 across:566264k
[ 14.038472] udev: starting version 151
[ 14.659640] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
[ 14.809245] sis96x_smbus 0000:00:02.1: SiS96x SMBus base address: 0x0c00
[ 14.822178] Linux agpgart interface v0.103
[ 15.190472] agpgart-sis 0000:00:00.0: SiS chipset [1039/0741]
[ 15.416183] lp: driver loaded but no devices found
[ 15.678321] agpgart-sis 0000:00:00.0: AGP aperture is 64M @ 0xd0000000
[ 15.774554] psmouse serio1: ID: 10 00 64
[ 16.102247] vga16fb: initializing
[ 16.102264] vga16fb: mapped to 0xc00a0000
[ 16.102556] fb0: VGA16 VGA frame buffer device
[ 16.378438] input: ImPS/2 Generic Wheel Mouse as /devices/platform/i8042/serio1/input/input4
[ 16.528414] type=1505 audit(1300688951.493:2): operation="profile_load" pid=711 name="/sbin/dhclient3"
[ 16.529057] type=1505 audit(1300688951.493:3): operation="profile_load" pid=711 name="/usr/lib/NetworkManager/nm-dhcp-client.action"
[ 16.529421] type=1505 audit(1300688951.493:4): operation="profile_load" pid=711 name="/usr/lib/connman/scripts/dhclient-script"
[ 17.132924] Console: switching to colour frame buffer device 80x30
[ 18.475021] alloc irq_desc for 18 on node -1
[ 18.475032] alloc kstat_irqs on node -1
[ 18.475053] Intel ICH 0000:00:02.7: PCI INT C -> GSI 18 (level, low) -> IRQ 18
[ 18.621143] eth0: Media Link Off
[ 18.623959] ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 18.812139] intel8x0_measure_ac97_clock: measured 55859 usecs (2686 samples)
[ 18.812152] intel8x0: clocking to 48000
[ 18.959269] type=1505 audit(1300688953.921:5): operation="profile_load" pid=1086 name="/usr/share/gdm/guest-session/Xsession"
[ 18.989074] type=1505 audit(1300688953.953:6): operation="profile_replace" pid=1088 name="/sbin/dhclient3"
[ 18.989773] type=1505 audit(1300688953.953:7): operation="profile_replace" pid=1088 name="/usr/lib/NetworkManager/nm-dhcp-client.action"
[ 18.990165] type=1505 audit(1300688953.953:8): operation="profile_replace" pid=1088 name="/usr/lib/connman/scripts/dhclient-script"
[ 19.125180] type=1505 audit(1300688954.089:9): operation="profile_load" pid=1091 name="/usr/bin/evince"
[ 19.140928] type=1505 audit(1300688954.105:10): operation="profile_load" pid=1091 name="/usr/bin/evince-previewer"
[ 19.147856] type=1505 audit(1300688954.109:11): operation="profile_load" pid=1091 name="/usr/bin/evince-thumbnailer"
[ 20.566652] ppdev: user-space parallel port driver
[ 82.196035] usb 1-6: new high speed USB device using ehci_hcd and address 2
[ 82.331890] usb 1-6: configuration #1 chosen from 1 choice
[ 82.588568] Initializing USB Mass Storage driver...
[ 82.591724] scsi2 : SCSI emulation for USB Mass Storage devices
[ 82.593196] usbcore: registered new interface driver usb-storage
[ 82.593208] USB Mass Storage support registered.
[ 82.607341] usb-storage: device found at 2
[ 82.607352] usb-storage: waiting for device to settle before scanning
[ 87.604815] usb-storage: device scan complete
[ 87.605620] scsi 2:0:0:0: CD-ROM HSUPA MMC Storage 2.31 PQ: 0 ANSI: 2
[ 87.606199] scsi 2:0:0:1: Direct-Access HSUPA MMC Storage 2.31 PQ: 0 ANSI: 2
[ 87.614748] sr2: scsi-1 drive
[ 87.617114] sr 2:0:0:0: Attached scsi CD-ROM sr2
[ 87.617783] sr 2:0:0:0: Attached scsi generic sg3 type 5
[ 87.618730] sd 2:0:0:1: Attached scsi generic sg4 type 0
[ 87.631133] sd 2:0:0:1: [sdb] Attached SCSI removable disk
[ 88.902556] usb 1-6: USB disconnect, address 2
[ 89.252032] usb 1-6: new high speed USB device using ehci_hcd and address 3
[ 89.386713] usb 1-6: configuration #1 chosen from 1 choice
[ 89.545868] scsi3 : SCSI emulation for USB Mass Storage devices
[ 89.583200] usb-storage: device found at 3
[ 89.583210] usb-storage: waiting for device to settle before scanning
[ 94.580705] usb-storage: device scan complete
[ 94.581628] scsi 3:0:0:0: CD-ROM HSUPA MMC Storage 2.31 PQ: 0 ANSI: 2
[ 94.582191] scsi 3:0:0:1: Direct-Access HSUPA MMC Storage 2.31 PQ: 0 ANSI: 2
[ 94.589975] sr2: scsi-1 drive
[ 94.590451] sr 3:0:0:0: Attached scsi CD-ROM sr2
[ 94.590711] sr 3:0:0:0: Attached scsi generic sg3 type 5
[ 94.594026] sd 3:0:0:1: Attached scsi generic sg4 type 0
[ 94.600199] sd 3:0:0:1: [sdb] Attached SCSI removable disk