In the past few years, I've kept a Google Nexus 4 smartphone (Android) in my workshop, ready to go with me on any trip overseas. Once I arrived at my destination, where I'd spend a couple of weeks to a month, I'd head to the airport's phone store, where the store staff would give or sell me a SIM card. This SIM card would let me use my Nexus 4 phone on GSM networks. It is a quad-band GSM phone, unlocked. In simpler terms, this phone works on just about all cell phone operator's networks throughout the world, but on the slower 3G networks. In the US, GSM operators are AT&T and T-Mobile. Verizon and Sprint phones were CDMA, not GSM, meaning their phones would generally not work overseas.
Most overseas operators use GSM technology. With an unlocked GSM smartphone like the Nexus 4, I could put any operator's GSM SIM card in my phone, pay for data and voice/text package, and within a few minutes (thanks to the expert staff), my phone would be ready to go. I could get email on the phone, make calls, and browse the Internet. I could even use the phone as a Wi-Fi hotspot.
(An unlocked phone is not tied to a particular carrier. A phone that is locked will ONLY work on AT&T's network, for instance, unless AT&T gives you a code to allow you to unlock your phone).
The above has worked for me for the past few years. Nearly all good Android phones, like Motorola’s Moto G and Google's Nexus phones (made according to Google specifications by companies like LG and Asus) are unlocked and are quad-band. Newer phones are able to run on the faster 4G LTE network -- but I won't discuss this here.
The one thing that I'd like to get across with the above is that anyone traveling to South Africa, Papua New Guinea, or the UK (all places I've recently spent weeks and months in) can bring a quad-band, unlocked smartphone, buy a SIM card, buy a data/calling package in that country, and be set. I've gotten emails on a boat sailing in the farthest reaches of Papua New Guinea -- amazing.
On my recent trip to South Africa, I brought my trusty old Nexus 4 phone. However, I also brought a Google Fi phone. Anyone who travels internationally a lot should consider buying a phone that works with the Google Fi plans.
Google Fi phones are designed to work in 130 countries around the world. I bought a Google Fi phone (a Nexus 5X phone) to use in South Africa. It worked great. I landed in Dubai and London during my flights, turned on the phone, and was able to use the phone in all three countries almost immediately.
Google Fi phones are world phones, meaning you can use them all over the world, in over 130 countries. You just turn on the phone and it generally starts working. You can use your Google Fi phone in the US, then go to China and use it without any hassle, and other countries like Taiwan and South Africa, England, etc. Someone can call you on this Google Fi phone (a US number) and it will ring you in China. It is a full-featured Android phone.
In the US Google Fi phones use both the Sprint and T-Mobile network.
Here are the rates and countries that Google Fi phones will work in:
The rates are extremely reasonable. Each month you pay $20 for voice and texts in the US. If you use data, you are billed only for the data that you use, at $10 per Gb. Calls to and from China are $0.20 per minute; for instance. When I used this phone in South Africa, calls were $0.06 per minute.
It took quite a bit of experimentation to figure out how to use these phones to call within South Africa and back to the US. Here's what I figured out:
1. Nexus 4 phone with local Vodacom SIM card. The key to using a phone to make calls internationally is to realize where the SIM card in your phone has originated. With a local SIM card in my Android phone, I needed to dial phone numbers like I was using a local South African (SA) cell phone. For some reason I needed to dial the country code (27) first, then the number in South Africa. I stupidly bought a data-only package at the Johannesburg Airport (JNB) when I arrived, so I had to use Google Hangouts Dialer to make phone calls. Here's what I did.
For instance, there's a hotel near Johannesburg Airport. The website lists its phone as "Phone: +27 11 394 5555" (not the real number). Another hotel, near Kruger National Park, had its phone number listed as "011 27 087 550 5555."
To reach these numbers in South Africa using my Nexus 4 phone, I needed to dial (using Google Hangouts Dialer): "27 11 394 5555" or "27 87 550 5555." I did not dial any "0's" at the beginning of the numbers.
My friend Andy had my Google Fi phone at times. This was a US number in the form 831-789-5555. For me to call him using my Nexus 4 (with a local SA SIM card), I had to dial "00 (the SA code to call internationally) then the US country code, and then the US phone number, e.g. "00 1 831-789-5555."
Note that if I am using a US landline to call a SA number, then I need to dial "011" in the US to indicate that I am calling overseas, then the country code of 27, then the phone number. Because my Nexus 4 had a local SA SIM card, to call the US, I needed to first dial the international code of "00" and then the US area code and number.
2. Google Fi Nexus 5X phone.
The Google Fi phone was activated in the US. It had a US phone number. Whether I used the phone dialing app or Google Hangouts Dialer, I did the same thing.
To call a number in South Africa, I had to realize that my Google Fi phone was US-based. Therefore, to call a hotel with the number "+27 11 394 5555", I had to dial "011-27 11 394 5555". In other words, I called by dialing the international US code of 011, then the country code for SA of 27, then the SA phone number. I normally did not dial any initial "0's" in any phone number.
My Nexus 4 phone with the local SA SIM card had the phone number of 079 082 8403. To call this phone using my Google Fi phone, I dialed 011 27 79 082 8403.
Calling a US number, like home, using my Google Fi phone was simple. I just dialed the area code and phone number! I was able to do this, again, because the Google Fi phone "thinks" it is based in the US.
I hope that the above helps travelers trying to figure out how to call within a country or back home when traveling internationally. The key is to figure out where your phone was activated and where your phone thinks is "home."