# Quick question: ISD codes and international roaming

Gold Member
Suppose a person goes from his homeland to some other country. He has a phone number registered in his homeland. Now, someone from his homeland (or any country except his destination) wants to call him over the phone. What ISD code should be used - the one of the person's homeland, or that of the person's destination?

As an example, say I travel to the USA. I have a mobile number that is registered in my homeland (India). Now, someone from my country wants to call me. Should that person prefix "+91" (ISD code for India) or "+1" to call me?

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fresh_42
Mentor
The person who calls you cannot know your present location, at least theoretically. So he simply calls your usual phone number and the telephone company directs it to where you are. So +91 is the answer. It should work even without it. The US code is only necessary, if a phone registered in the US is called, e.g. non mobile phones, or if you chose to buy an American contract.

The costs on the other side is a different question. It usually costs extra fees for your friend to reach you as some networks of third party companies need to be used. I cannot tell the exact distribution of costs, as this depends on too many unknowns, but it can get quite expensive.

davenn and Wrichik Basu
Gold Member
It should work even without it.
For the inverse, that is, if I call someone who is in India while I am still in the US, I have to prefix the isd code of India, right?

fresh_42
Mentor
Right, you have to use +91, or 0091. But again, it can be rather expensive. It took the EU several years until they regulated the roaming costs for phone calls and for SMS, which in some cases had been ridiculously high.

Wrichik Basu
Gold Member
Right, you have to use +91, or 0091. But again, it can be rather expensive. It took the EU several years until they regulated the roaming costs for phone calls and for SMS, which in some cases had been ridiculously high.
Costs are quite high, I agree. Indian mobile operators have unusually high rates, but they also have some packages, giving you some fixed time of call for some fixed money. Dad would be travelling to Dubai this week; that's why these questions arose.

DrClaude
Mentor
Right, you have to use +91, or 0091.
In the US, the prefix for an international call is 011, not 00.

Wrichik Basu
davenn
Gold Member
2019 Award
I cannot tell the exact distribution of costs, as this depends on too many unknowns, but it can get quite expensive.
Costs are quite high, I agree

maybe you need to shop around for better deals ....

I'm with Vodafone Australia, my roaming for calls and data are dirt cheap. They have the most popular 20 countries on their list
and if I am in one of those countries it only costs me $5 per 24hrs or part thereof of use. I have used it travelling to USA, New Zealand and to South Africa. If there is a full 24 hrs of non-use ( never happens) during my say 2 week trip, then that is$5 less to pay
for each of those periods..
It includes my full data usage up to my max monthly data allowance (40GB) so as a result, not only do I use it for occasional
phone calls, it gets used every day for internet access ( use my phone as a WiFi hotspot and connect my tablet etc to it)

My last trip was to NZ last March for 9 days so all I paid was an extra \$45 on my phone bill

as far as actual numbers dialled......
Some one calling me (regardless of where they are) call my number as tho I am at home in Australia -- doesn't cost them any extra
If I call an Australian number - I call them as I would if I was in Australia
If I am in New Zealand and calling a NZ number, I can call using the full prefix eg 0011 ( gets out of AU) 64 ( NZ country code)
then the area code 3 and actual phone # so 0011643 4xxxxxx or I can just do +643 4xxxxxx

Dave

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