Any overseas travelers out there who need to keep in touch?

[Leafgreen]

I got married two weeks ago! I plan to be in Serbia with her for two weeks in May.

I need to make and receive calls for business while there. How can I do that affordably?

Here are the important points:
When someone calls my USA phone number, I need to answer the call in Serbia. From there, it gets more complex...

The source of most of my incoming calls are to a Google Voice ("GV") number (xx7 for short here), not a real landline or carrier-provided number. That number is being forwarded to another Google Voice number: (xx8 for short here). And, xx8 is being forwarded to xx1, which is my Sprint cell phone number.

Although Sprint provides overseas calling options, I absolutely cannot use xx1 overseas because it is provided by a business partner. Instead, consider that for two weeks I can get a new smartphone (Android preferred) either here in USA or in Serbia.

If I change the forwarding routing as described above, it must be from xx8 to a new number other than xx1, possibly a new phone that I get in USA or Serbia. If Serbia, can I forward from a USA GV number to a Serbian cell phone number? This is the first thing I need to know, I guess.

Surely there must be other options! Ringcentral?

I guess putting a SIM from Serbia into my phone will provide me with a Serbia phone number. This doesn't solve the problem. Although it does make me think that I can replace the SIM on my Samsung Galaxy S5, which might be helpful to accomplish my calling goals.

For outbound calls from Serbia, the least expensive method is probably Magicjack. But, I must use it at a computer with Wi-Fi. That's ok when I am there, but I must have an outbound option when I am away from a computer and Wi-Fi. How: Also, the phone number that people see on their phone or CallerID when I call them should be a USA number, otherwise they may not answer.