I also faced the same issue, but somehow it worked for me after some tweaking.
Solution 1: (If you have access to Windows Machine)
Just go to the Reliance Netconnect Plus UI in Windows machine and in Settings change the 'Mode' to 'Hybrid'.
By doing this I found that the Reliance Netconnect Plus is recognized by Ubuntu quickly and
Now log in back to Ubuntu and connect to the internet through 'Network Manager'.
Using this method you will be registered on CDMA home network and can access the internet quickly.
The main disadvantage of this method is that we are running it under 'Hybrid' mode, which means that the internet may switch to 'CDMA 1x' mode and the internet speed will go down.
For me this happens only for 5-10 minutes then I'm again switched to fast Netconnect+ mode.
To overcome this disadvantage you may use Solution 2.
Solution 2: (Using WVDIAL)
If the Reliance Netconnect Plus modem works in Solution 1 then after connecting to internet, install WVDIAL
If you have access to GSM mobile(or GSM Modem) with cheap GPRS plan, then connect your mobile to Ubuntu through Network Manager and install WVDIAL. I have never experienced any difficulty with GSM Modem when connecting to Internet through Network Manager.
(i) Open Terminal (Keyboard Shortcut: Ctrl + Alt + T ) and type
sudo apt-get install wvdial
(ii) Open up wvdial’s configuration file using this command
(iii) Paste the below code into the window that pops up ( make sure to enter your relevant details )
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Stupid Mode = 1
Modem Type = USB Modem
ISDN = 0
Phone = #777
New PPPD = yes
Modem = /dev/ttyUSB0 (This may also be dev/ttyUSB2 depending on where you plugged in your device)
Username = 9xxxxxxxxxx (your username, should be a number )
Password = 9xxxxxxxxxx (Your password , should be the same number)
CBaud = 460800
Delete all the comments in the brackets . The fields you should edit are Modem , Username and password the only ones with comment .
Save and exist .
(iv) Thats it. Remove the GSM mobile(or GSM Modem) from PC/laptop and plug in Reliance Netconnect+ Modem. Wait till it gets recognized by Ubuntu, run lsusb command to know if it detected as modem and then
Run wvdial using following command
Internet using wvdial works out of box. Now you can change the Network Mode to 'Netconnect+' by using Reliance Netaconnect Plus UI in windows and log back to Ubuntu to use the uninterrupted broadband using wvdial.