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What is a dual SIM phone

Phone advice | by Denise Timmis | Feb 18, 2022

What is a dual SIM phone

Every smartphone has a SIM card and won't work without it. It's the tiny 'brain' that connects the device to the network. If you've researched smartphones recently, you may have noticed that some are described as dual SIM phones and be wondering what that means. Why would anyone need more than a single SIM?

At Envirofone, we're experts at refurbishing phones, which makes us all-round experts in smartphone technology. So here's our quick guide to what a dual SIM phone is, and why you might find one useful.


What is a SIM card?


The SIM (subscriber identity module) card is that little piece of plastic containing a microchip that slots into a slide-out tray on your phone. Insert a SIM and the phone springs into life. It carries the MSISDN (Mobile Subscriber Integrated Services Digital Network Number) which tells the network that this is your device, and makes your unique phone number work.

The SIM also stores contact information, telephone numbers, SMS messages, billing information, your data usage record and the personal identification number (PIN) that stops other people from using your phone. That's why, if your smartphone malfunctions, you can simply transfer the SIM to another handset and...hey presto, that's your phone!


Why choose a dual SIM phone?


If you want two phone numbers on the same device, one for work and one for personal use perhaps, a dual SIM makes this possible. Anyone who has ever struggled to juggle different handsets will understand the appeal of having two phones in one.


People also choose a dual SIM so they can alternate between two networks or two different contracts on the same network. There can be various reasons for this, such as:


  • One network doesn't provide adequate coverage in some locations.
  • One network or contract offers the best value for voice calls, whereas the other is better or cheaper for internet usage, so a dual SIM can save you money.


How do dual SIM phones work?


There are two types of dual SIM smartphones Dual SIM Dual Standby (DSDA) and Dual SIM Full Active (DSFA). The first type puts one SIM on standby when the other is in use, so if anyone rings that number they see it as engaged. DSFA allows both SIMs to be active at the same time, so you can be on two calls at once and jump between them.

Most dual SIM phones have traditionally had a tray that physically holds two cards, but eSIM devices are becoming more common. The e stands for 'embedded' and, as that suggests, the eSIM is built-in and not removable. The advantage is that you can run two different networks and/or numbers without the faff of inserting two cards.

Does the iPhone have dual SIM?


Until recently only certain Android phones offered a dual SIM option. But nowadays Apple iPhones that run iOS 13 or later include an eSIM, which means they can be used as a dual SIM phone.


Can dual SIM phones be on different networks?


Some phones are locked to a particular network, but any unlocked phone with dual SIM capability can run on different networks. All refurbished smartphones from Envirofone are guaranteed to be unlocked. So choose any dual SIM phone from us and you're free to use two networks at the same time.


What's the best dual SIM phone to choose?


It's impossible to recommend a single phone, as it depends on your personal preferences. However, among the models critics picked out as the best dual SIM phones in 2020 were the OnePlus 8 Pro (best for performance) and the Samsung Galaxy S20 (best for features).


In truth, all the leading manufacturers including Samsung, Huawei, OnePlus and Apple now offer superb dual SIM phones Our advice is to keep checking the choice here at Envirofone. You'll always find a wide range of expertly refurbished smartphones with exceptional savings.



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