Can’t make or receive calls abroad (in Taiwan) — PAYG SIM

[Kevvvv116]

Hi everyone,

I’m using an O2 Pay As You Go SIM that I got in the UK. I was able to use it normally while I was in the Netherlands (both calls and data worked fine).

However, I’m currently back in Taiwan, and now I can receive SMS messages, but I can’t make or receive any phone calls. When I try to call someone, there’s no dial tone or system message — just complete silence.

This is a big issue because I’m expecting an important interview call soon.

I’ve already checked that:

• Airplane mode is off
• Signal bars are visible
• Roaming is turned on
• I have enough credit

Could anyone please help me figure out what might be wrong or how to get calls working again while I’m in Taiwan?

Thanks a lot in advance! 🙏

[MI5]

@Kevvvv116 

You need a 3g network to make calls on PAYG, at least until O2 roll out 4g calling.

Manually search for a network still providing 3g or lock the phone to 2g if you can.

[Kevvvv116]

Thanks a lot for your quick reply!

However, Taiwan completely shut down all 3G networks around mid-2024, so there are no 3G base stations left here. That might explain why I can receive SMS but not make or receive calls.

Is there any workaround for this situation? For example, does O2 plan to roll out 4G/VoLTE calling for Pay As You Go users, or is there a way to temporarily enable Wi-Fi calling? I have an upcoming interview and really need to stay reachable.

Thanks again for your help! 🙏

[Enlli]

As to VoLTE and WiFi Calling all we are told is a vague 'by the end of the year.' No way to activate it yourself

If Taiwan still have 2G then it may work locking the phone down to that (probably not possible on iPhone) Otherwise put the SIM in a cheap 2G dumb phone if the call is important 

[madasaf1sh]

@Kevvvv116 

All we know is by the end of 2025 but I can see that been pushed back, but PAYG has always been the poor relation to Pay Monthly

Your only option, is to buy a local sim and use whatsapp or the like. 

[MI5]

@Kevvvv116 

This is what O2 say about it.

I'm on Pay As You Go. What do I need to do?

If you're on Pay As You Go, and your phone or SIM doesn’t support 4G Calling (VoLTE), you may lose the ability to make and receive calls once 3G is switched off in your area - even if you still have signal for texts and data.

To stay connected after the 3G switch off:

• Make sure you're using a 4G or 5G compatible phone

• Check that 4G Calling is enabled in your phone settings

• Some older SIMs may need replacing to support these features. Please contact your local O2 store for support

4G & WiFi calling will be available for Pay As You Go customers by the end of 2025. To access it before then, you'll need to switch to Pay Monthly.

From here https://www.o2.co.uk/help/international-and-network/network-and-coverage/3g-switch-off