Unable to connect to the internet on a Ubuntu 14.0.4 laptop using zte(reliance cdma) AC2739 USB modem‏

I had a pretty similar problem with my ZTE USB modem and it turns out it was getting mounted as a CD unit.

This is how I solve it:

Step 1: Use lsusb to verify your usb modem is detected

sergiotca@sergiotca-Dell-System-XPS-L502X:~$ lsusb
Bus 002 Device 003: ID 8086:0189 Intel Corp. 
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 003: ID 046d:c07e Logitech, Inc. 
Bus 003 Device 009: ID 19d2:2000 ZTE WCDMA Technologies MSM 
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0408:2fb1 Quanta Computer, Inc. 
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Step 2: Use dmesg | tail to know how it has been detected

sergiotca@sergiotca-Dell-System-XPS-L502X:~$ dmesg | tail
[ 6136.744009] usb 3-1: Manufacturer: ZTE,Incorporated
[ 6136.744012] usb 3-1: SerialNumber: MF1800ZTED010000
[ 6136.747257] usb-storage 3-1:1.0: USB Mass Storage device detected
[ 6136.747504] scsi19 : usb-storage 3-1:1.0
[ 6137.748200] scsi 19:0:0:0: CD-ROM            ZTE      USB SCSI CD-ROM  2.31 PQ: 0 ANSI: 2
[ 6137.751676] sr1: scsi-1 drive
[ 6137.752168] sr 19:0:0:0: Attached scsi CD-ROM sr1
[ 6137.752731] sr 19:0:0:0: Attached scsi generic sg2 type 5

Step 3: Use usb_modeswitch to change the mode of your usb modem by "ejecting it" using the -K parameter. Use the vendor and product ID from your own modem (lsusb)

sergiotca@sergiotca-Dell-System-XPS-L502X:~$ sudo usb_modeswitch -v 0x19d2 -p 0x2000 -K
[sudo] password for sergiotca: 
Look for default devices ...
   product ID matched
Found devices in default mode (1)
Access device 010 on bus 003
Current configuration number is 1
Use interface number 0
Use endpoints 0x01 (out) and 0x81 (in)

USB description data (for identification)
-------------------------
Manufacturer: ZTE,Incorporated
     Product: ZTE WCDMA Technologies MSM
  Serial No.: MF1800ZTED010000
-------------------------
Sending standard EJECT sequence
Looking for active driver ...
 No active driver found. Detached before or never attached
Set up interface 0
Use endpoint 0x01 for message sending ...
Trying to send message 1 to endpoint 0x01 ...
 OK, message successfully sent
Read the response to message 1 (CSW) ...
 Response successfully read (13 bytes).
Trying to send message 2 to endpoint 0x01 ...
 OK, message successfully sent
Read the response to message 2 (CSW) ...
 Response successfully read (13 bytes).
Reset response endpoint 0x81
Reset message endpoint 0x01
-> Run lsusb to note any changes. Bye!

Step 4: Finally use dmesg | tail to verify that your usb modem has changed to Direct-Access mode

sergiotca@sergiotca-Dell-System-XPS-L502X:~$ dmesg | tail
[ 6874.527436] usb 3-1: GSM modem (1-port) converter now attached to ttyUSB0
[ 6874.527700] option 3-1:1.1: GSM modem (1-port) converter detected
[ 6874.527894] usb 3-1: GSM modem (1-port) converter now attached to ttyUSB1
[ 6874.528148] option 3-1:1.2: GSM modem (1-port) converter detected
[ 6874.528305] usb 3-1: GSM modem (1-port) converter now attached to ttyUSB2
[ 6874.528510] usb-storage 3-1:1.3: USB Mass Storage device detected
[ 6874.528704] scsi20 : usb-storage 3-1:1.3
[ 6875.529082] scsi 20:0:0:0: Direct-Access     ZTE      MMC Storage      2.31 PQ: 0 ANSI: 2
[ 6875.532997] sd 20:0:0:0: Attached scsi generic sg2 type 0
[ 6875.535452] sd 20:0:0:0: [sdb] Attached SCSI removable disk

Step 5: Your modem should be detected now by the network manager.

after analyzing System logs carefully this solution worked for me

Cause Of Problem: Multiple modes of modern dongles.

Solution:
1.

gedit /etc/usb_modeswitch.conf

2.add this code to diable usb switching at the top.

DisableSwitching=1

3.save it.
4.insert usb again
5.eject usb cdrom by right click eject it
or using.

sudo eject /dev/sr1

6.Wait for 5-10 sec(time to detect it as modem) 7.now go to network manager
8.Reliance network will be listed in network manager connect to it by creating new connection.
7.now go to network manager
8.Reliance network will be listed in network manager connect to it by creating new connection.

that's all

Reliance provide UI software also
simply install it using