Wondering whether SIM slot 1 and SIM slot 2 are any different, and if so, how? Don’t fret, we’ll clear up that for you. You should know that it truly depends on the model of the phone itself. To reduce production costs, and thus theoretically charge less, many manufacturers choose to skimp out on features. And, unfortunately, the presence of multiple SIM slots inside one phone is one of those. You should always verify which of the cases below is yours, either by doing your own research or asking other phone owners or the seller. Here’s the difference between SIM slot 1 and 2 – where it exists, that is.
Case 1. There’s no difference between two SIM slots
This is the ideal scenario, where both SIM slots have an identical level of functionality. Thankfully, it’s becoming widespread with all common network types – CDMA, GSM, LTE, etc. Three common examples when SIM slot 1 and slot 2 have no differences are:
1. 4G or 3G
A phone that can achieve 4G or 3G connectivity on both SIM cards, only one slot at a time or simultaneously.
If your phone is “dual voLTE capable”, it means both SIM cards can use voLTE (Voice over LTE) which significantly improves call quality. Based on your device, you might be able to use it on both SIM cards concurrently or only on one slot at once.
3. SIM card size
To sum things up, if you have a dual SIM phone and it falls under case 1, it’s just the specifics that vary. At its core, it doesn’t matter whether two SIM cards share the same golden contact (Dual SIM Single Standby or Dual SIM Dual Standby) or have a separate one (Dual SIM Dual Active) since both slots for SIM cards are equally capable.
Case 2. 4G/3G/2G network limitation
Although it’s slowly going away, this case is especially common with cheap models in third-world countries where there’s a need to have 2 or more SIM cards on standby. To keep the cost down, manufacturers only allow the primary SIM card to access 4G LTE speeds. The SIM card in slot 2 can only achieve 3G or 2G connectivity and speeds. In older models, the main slot is limited to 3G, while the secondary can only detect 2G. No amount of tinkering will change that, so your only option is buying a new device.
Case 3. SIM card size differences
These are the two main differences between slot 1 and 2 regarding the SIM card size:
Physical SIM card slots aren’t identical
This is rare and only implemented in old models or cheap knock-off models from China. There’s a possibility that one SIM card slot allows a micro-SIM card while the other allows you to insert a nano-SIM card. Similarly, you might see a mini-SIM/micro-SIM combination in the specs sheet. If this is the case, there’s a strong chance the network limits from case 2 apply as well.
One SIM card slot is embedded
You must’ve seen this option in the specifications on newer phones. One SIM card slot is already filled with an embedded SIM card that cannot be removed physically. Only slot 2 allows you to insert a SIM card of another size except for eSIM. Other than that, there are usually no other differences.
Case 4. Carrier limitations
Regardless if two slots follow case 1 or case 2, if you bought a SIM card from one carrier and inserted it into slot 1, you likely cannot use a SIM card from another carrier in slot 2. It doesn’t matter that it fits into the slot perfectly and that it supports the network your phone is capable of. The only way to use two different providers in two SIM slots is to unlock a SIM card or rather the phone itself.
Case 5. 5G connectivity limit
People have asked us this repeatedly, so here’s an answer. Newer phone models that support 5G and have a dual SIM feature often fall under case 1. However, even though your phone is capable of DSDS and DSDA, it lacks the bandwidth required for 5G when both SIM cards are in use. For that reason, you have to resort to using only SIM slot 1 or SIM slot 2. This will change as the phone hardware grows more powerful.