问题
I am developing an application which requires to keep track of the outgoing calls made by user, which I am able to track by Using Broadcast Receiver. I also want to detect that is that call is Local or STD or ISD, but I am not able to detect that.
回答1:
Suppose, you know to which State(Telecom Circles) the outgoing call is going. Then you just need to check if your Local-State(Telecom Circles) is same as Outgoing-call-State(Telecom Circles) or not. If it is same, then local call else STD calls.
Now, the problem boils down to, how to find the State(Telecom Circles) of an outgoing-calls.
This can be easily done for Landline phones where we specifically put STD codes. See the link for state and there STD codes.
Interestingly, mobile phones also follow something very similar. First 4 digits of a mobile number tells that. For e.g suppose the number is 9999xxxxxx, then this number is from Delhi - Vodafone. See the wikipedia link for complete mobile phones first 4 digit details.
来源：https://stackoverflow.com/questions/15109329/how-to-determine-a-call-made-is-local-or-std-or-isd