android : can we call from Android to another platform and vice versa using VOIP

Can we call from Android to another platform and vice versa using VOIP?

I konw that 开发者_如何学Cusing SIP, one android device can make call to another android device. But I am not sure about calling to other platform like iPhone. Is it possible?

And also, whether the caller and recipient should have same SIP domain?

I would appreciate any suggestions and help....

Thank you...

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SIP is a protocol independent of the platform. So yes you can call from Android to iPhone to Windows to Linux to whatever you want provided you have correctly implemented the sip stack.

Yes all of them need to be registered to the same SIP domain or their servers should have configurations to talk to each other.