How to use it
  1 Before you leave, check that your roaming function has been activated, by calling our Customer Service Centre (Call Toll Free Number 1503).
  2 After landing into foreign country, switch ON the phone and go to Menu. Click on Cellone or BSNL Mobile and select Network.
  3 In the network you will get option of National and International. Select International, you will get CellOne and Partner Network.
  4 Select the option Cellone, you will get a message - "CellOne International Selected". Wait for two minutes you will get the Network automatically.
  5 If it fails, please select the network manually.(By selecting Setting and then Network in your phone).
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   d Basic checks - Before you go
   
Before you leave, check that your roaming function has been activated, by simply calling our 24 hours customer service helpline 1503.
Make sure your handset will work in the country you're travelling to. Please check the Handset compatibility with Network frequency (GSM MHz 850/900/1800/1900) before travelling outside India. Japan & Korea support 3G Hand Set, USA & Canada supports 1900 MHz Hand Set.
To call back home dial the number with “+91”.
To access Voicemail abroad, you need to set up a Voicemail PIN code. To do this, access your Voicemail in the India and follow the voice prompts.
You can alert your callers that you are overseas by activating a Caller Tune announcing that you are overseas. Dial 56700 and select the English category.
Certain GPRS based applications viz. GPS, Facebook, Blackberry messenger or any other instant messaging application etc. continuously consume data bandwidth leading to high Data-Roaming charges even when you are not using the same. This is applicable to smart phones and high-end GPRS capable handsets which poll (communicate with) the home network continuously. We advice you take an informed decision to keep these applications switched-on, while you are overseas. For any assistance in the matter, please call our customer helpline.
   
d Making calls when you're abroad
   
Calling a number in the country you're visiting :
Dial the full number, including area code, as you would at home.
 
Receiving calls when you're abroad :
The same as when you're in the India — except you're charged when you receive calls.
 
Calling another country when you're abroad :
Dial '+ ' followed by the country code, then key in the phone number without '0'. For example, to call from US to UK, dial +4412345678.
   
d Sending text messages
   
Works exactly the same as when you're in the India.
SMS is charged for 160 characters per outgoing SMS e.g., if an SMS is of 200 characters then it is charged as two SMS’s.
Don't forget to dial the full international number, including the 91 prefix.
If your mobile is not working, even then you can send SMS. Click here.
   
d GPRS/Data Roaming
   
The charges for GPRS/Data usages are calculated in terms of the Volume of data sent or received. As with the Voice/SMS, charges here are variable and completely dependent on foreign operators. Also note that your local plans for GPRS/Blackberry are not valid overseas and all data usages are charges at the visited operator rates.
d Blackberry
   
Receiving and sending mails, while you are on international roaming, add to data usage and therefore, are charged accordingly.
Your local unlimited plan for GPRS/Blackberry is not valid overseas.
   
d Billings and Payments
   
While you are roaming overseas, as a service gesture, BSNL does not normally restrict your usage to the extent of your credit limit. This is done to allow you continued access, considering the significantly higher usage charges in international roaming.
To get periodic updates on usage, subscribe to our free usage alerts service by sending an SMS “USG” to 53333. The charges incurred by you, while on international roaming, are sent to us by international operator and can take 3 days or even more and accordingly the alerts received by you may not reflect the latest status and will be as per the last update received by us.
   
d Getting help when you're abroad
   
If you encounter any difficulties while on International Roaming you can book your complain Click Here OR Call +919434024365.