Two numbers, one phone: the benefits of dual SIM devices

Two SIM cards in one phone – dual SIM phones offer a simple, practical function for heavy users of smartphones. — dpa

Two SIM cards in one phone – dual SIM phones offer a simple, practical function for heavy users of smartphones.

And it's not just for smartphones. Dual SIM phones are also available in classic mobile phones. Many manufacturers like Samsung and Nokia offer cheap phones without special features in dual SIM variants.

But things get tricky for iPhone users. Most dual SIM devices run on Android operating system; a few use Windows Phone.

Who are these phones suitable for?

A dual SIM phone means that you have a personal phone connection and a business or work one in the same device.

These phones can also suit people who regularly travel between two countries or who have family or close friends in another country. In these situations having two SIMs should help to keep costs down.

How do they work?

The operating system of a dual SIM device allows users to quickly switch between the two numbers. When you’re making a call you can decide from which number to make the call. And the user is reachable via both numbers simultaneously.

"Some models offer the option of deciding from which number to send each text message," says Michael Peuckert from the trade magazine Connect.

What are the limitations?

That depends upon the model. Generally, the two SIM card slots don’t have the same functionality. Fast internet via LTE usually only exists for one of the two slots.

On the second SIM card you might only have a 2G or 3G connection, says Wolfgang Pauler, head of the test centre at Chip magazine. That will mean much slower data transmission on the second connection.

The simultaneous operation of two mobile phone connections also uses more energy than a single connection, a factor which can impact battery life.

What about messenger apps?

Messenger apps like WhatsApp identify their users via their phone number so these apps can only be installed once per phone. That means a dual SIM user has to choose one number or the other to use with messenger apps since they can’t use both.

However, newer Huawei smartphones offer an app-twin function which creates a copy of an app so that a second account can be created. Samsung’s Note 8 has a similar feature called Dual Messenger.

Another solution is to create a second user account, an option which is available on newer Android smartphones. But in that case the user has to switch between accounts to use the different phone numbers.

What is a hybrid slot?

Cheaper devices in particular have hybrid slots which can take either a second SIM card or a micro SD card for more memory. The best solution is to buy a device with two SIM card slots and one for a memory card, Peuckert says. — dpa