Before Voice over IP, when you travelled internationally, calls back to the US were usually really expensive. Long before I ever had a cell phone, I remember having to find a pay phone and use a calling card to get a somewhat discounted rate. No way would that have been practical for a business! Fast-forward to 2014 –Voice over IP has completely changed communications. While abroad, you could intercom with your office, as if you were actually there. Read on:
 

On your next trip, don’t forget to pack your desk phone

When you arrive at your destination, you ‘ll just need to plug your phone into an internet connection and you are able to receive and make calls from your usual office phone number.
For example: Say my number is 212-290-2736. That’s a number which is localized to New York City. However, I can literally take my desk phone with me, anywhere and call back to the NYC office, as if I were sitting at my desk. I’d be able to dial extensions, transfer calls, put calls on park, etc; all without paying any long distance or other charges. All I would need is a stable internet connection.
 

It’s a well-known fact that your desk phone won’t fit in your pants.

Also, you’re probably not going to take your desk phone on your trip with you. However, using a mobile application on your cell phone, you’ll be able to make and receive calls as if you were in your office back home. This requires a good WiFI connection, though.
 

Some things to be aware of:

1) If you take your phone abroad, you’ll always be calling from your home number. This means that, should you place a “local” call in the country where you’ve travelled to, the call will technically be considered long distance one, and you’ll pay long-distance rates.
2) Just like when you’re home, you need to have a reliable internet connection wherever you take your phone.
3) You will need a separate power adapter for your desk phone. While IP phones are commonly powered via their network connection, this requires special equipment which is unlikely to be found in most places.