Under Dual SIM Dual Active, both SIM cards are active at the same time. This allows you to make and receive phone calls from either SIM, at the same time. Even if you are on a phone call on one of the SIMs, you can receive a call coming in on the second SIM.

A phone can only be in Dual SIM Dual Active mode if it supports dual 5G and both the SIMs are working on VoLTE. 

What is dual VoLTE?

Dual VoLTE is a subset feature, allowing you to make HD calls from either SIM. If you have two SIM cards that both facilitate VoLTE, you can choose either SIM before making a call.

When a phone is in Dual SIM Dual Standby mode, both SIM cards are active and can make and receive calls while they are both in standby mode (i.e. neither are in use).

Once one SIM card is in use (i.e. you take a phone call), the other SIM card becomes inactive for the duration that the first SIM card is in use.

This is because the two SIM cards in Dual Standby phones use the same receiver. Once a call on one SIM card is engaged, it will use the receiver exclusively and the other SIM will lose mobile connection.

To avoid missing a calls from one SIM while the other is engaged, you can set up call forwarding.

An eSIM is a digital SIM embedded in your device, enabling you to activate your mobile plan without a physical SIM card. eSIM capable devices can support dual SIM functionality by using both a physical SIM and an eSIM, or two eSIMs if supported. This means you’re able to use two different mobile networks; one using the physical SIM slot and one using the eSIM.

This is different from Dual physical SIMs, which uses two physical card slots. To learn more about eSIM and the eligibility for Optus Customers read A guide to eSIM.

Having the ability to use two different mobile networks on the same mobile device is useful in several situations.

1. One phone for work and personal use

The benefit of using a dual SIM mobile phone is that you’re able to make and receive calls and SMS from both your personal and work phone, all on the one device, rather than having to carry around two separate mobile phones.

2. International travel

Dual SIM means you can take advantage of local plans while travelling overseas.

Dual SIM lets you stay connected to your Australian number while using a local or travel SIM overseas. eSIM makes it simple to add a travel plan on the go. 

3. Getting the best deal

Dual SIM means you can take advantage of the best mobile plans to suit your needs. You could use one SIM for a high data plan and the other for calls and text, without having to worry about the amount of data allowance. 

While dual SIM is a great benefit for business-people and travellers, there are some downsides.

In some phone models, the second SIM card slot takes the place of the microSD slot. In these circumstances you cannot use a microSD card to extend your phone’s storage space. If you want to avoid this potential problem, look for a dual SIM phone which has higher built-in storage space.

While you can make and receive calls and SMS from either SIM card in dual SIM phones, you can only have one active data connection to the internet. In the Settings section of your phone you are required to set your preferred SIM for connecting to the Internet.

There are a number of ways you can check if your phone is dual SIM:

1. Open the SIM card settings on your device and see if there are two options
2. Check the phone package for two IMEI numbers
3. Search for your phone in the Device Guides.

Yes. You can use just one single SIM card in a dual SIM phone. The second SIM card slot simply gives you the option to use a second SIM card if you would like.

When a phone is in Dual SIM Dual Standby mode, and one SIM is engaged in a call, you will miss any incoming calls from the other SIM that occur during the time that first SIM is engaged.

To overcome this issue, you can set up call forwarding between the two SIMs. See this page for instructions on how to set up call diversion on mobile phones.

For eSIM activation, just download your eSIM profile through My Optus app and activate in minutes.

If your phone is single SIM it cannot be converted into a dual SIM phone.

If your phone is dual SIM, you can activate it by inserting two SIM cards – one in the first SIM card slot, and a second SIM card in the second SIM card slot. The activation settings for dual SIM can be accessed in your phone’s settings.

You can turn off one SIM card in the settings section of your phone. The settings options may vary between devices. For dual SIM settings specific to your device, search your device in our Device Guides.

For dual physical SIMs, you can also remove the second SIM from the SIM card slot.