Singtel Wifi calling

[froztheart]

Simba is a documented no go on iPhone.
Eight is certainly working on iPhone early this year, no idea about now.
I believe I tested maxx and had it working, but not totally certain about it.

Oh is it? With this debacle I lost all memory of what was working and what's not. lol
Never tested Eight with IOS so have no data point.

Singtel 5G wifi calling on iOS has been working well for me. I am looking at it as I type this.

Wah, then what might be the issue then.
Can share what IOS are you on and what model just for me to better understand and pinpoint the issue I might have.

dunno about ios, but different telcos appear to have differing support for phone brands (or possibly models within the supported brand), and android versions

eg, on my home m1 broadband:
- Nothing phone 2: ok with gomo and simba, not with eight (i assume if suported on gomo, it will also be suported on the various singtel plans)
- Oneplus 11, 12, 13, 13R - ok with gomo, simba, eight.
- didn't test with maxx because the SIMs are in old pre-2020 phones where the telcos won't suport VoLTE)

on friends phones on their home broadband (m1, singtel, VQ):
- various Realme and Oppo A-series phones below the $400 price point when new: all ok on singtel sim only, simba, eight
- my phones when logged into their broadplan LAN, had the same VoWiFI as when tested at home.

hmmm.... there's no router settings that you fiddled with, yes?
The diference in support is PITA...

 

[GlassDoor]

Wah, then what might be the issue then.
Can share what IOS are you on and what model just for me to better understand and pinpoint the issue I might have.

ios 26.1 on 14 pro max. other family members on 15 pro, 16 pro max. all no issues. Singtel wifi calling triggers automatically when on home wifi. Home wifi is on VQ connection. I even tested on wireless@SG while queuing at hawker center a few weeks back. Singtel wifi calling will trigger automatically too.
the only period when I experienced issue was during april to July/August this year. when singtel 5G sim will not connect to wifi calling. this was due to singtel 5G migration. (details are there if you scroll further back on this thread).

Edit:
i can see the ikev2 connection on port 4500 from my iphone to the singtel wifi calling server

IPV4

UDP

<my_iphone_lan_ip>:4500

111.65.100.1:4500

42.41 KiB (548 Pkts.)

 

[loganrunning]

hmmm.... there's no router settings that you fiddled with, yes?

no router settings, apart from the usual password, setting static IP. all others like QoS disabled.
also running Merlin (but that made no difference as got the same results when at friends' homes, they run TP-Link, RT-BE92, one is a ubiquiti + asus routers used as AP etc)
Asus RT-AX88U btw.

The diference in support is PITA...

support is a cost centre........ the more painful they make it, the less likely you gonna call and disturb them.

 

[froztheart]

ios 26.1 on 14 pro max. other family members on 15 pro, 16 pro max. all no issues. Singtel wifi calling triggers automatically when on home wifi. Home wifi is on VQ connection. I even tested on wireless@SG while queuing at hawker center a few weeks back. Singtel wifi calling will trigger automatically too.
the only period when I experienced issue was during april to July/August this year. when singtel 5G sim will not connect to wifi calling. this was due to singtel 5G migration. (details are there if you scroll further back on this thread).

Edit:
i can see the ikev2 connection on port 4500 from my iphone to the singtel wifi calling server

IPV4

UDP

<my_iphone_lan_ip>:4500

111.65.100.1:4500

42.41 KiB (548 Pkts.)

no router settings, apart from the usual password, setting static IP. all others like QoS disabled.
also running Merlin (but that made no difference as got the same results when at friends' homes, they run TP-Link, RT-BE92, one is a ubiquiti + asus routers used as AP etc)
Asus RT-AX88U btw.



support is a cost centre........ the more painful they make it, the less likely you gonna call and disturb them.

Then what else might be the issue on my end wor...

 

[GlassDoor]

Then what else might be the issue on my end wor...

just curious. you doing anything to DNS request on your network?

 

[loganrunning]

Then what else might be the issue on my end wor...

how old is your iphone?

maybe that is a factor?
(on android, anecdotally telcos don't seem to support VoWiFi if older than 3-5 years)

 

[A7997A]

There is a few factors affecting wifi calling support :

1) Phone support of the Telco.
This is usually implemented in the software update of the phone.
The phone need to have the suitable profile for the telco, it does appears that some component of this can be generic profile, but there are some portion that is telco specific.

2) Telco support of wifi calling :
Starhub have full support even on the MVNO
M1 support on M1/Maxx but not CL. (no confirmation of it working for other M1 MVNO but irrelevant now)
Singtel only has it on the MNO network, none of the MVNO has it.
Simba unofficially supports on Android phones, doesn't work on iPhones.

For phones supported, telco can choose to whitelist/blacklist specific phone models, down to regional models.
If they do this it is usually either specific models that they sell, or year/models that they believe will work.
I suspect SG telco use free for all arrangement : good if it works, too bad if it doesn't.

3) Wifi network support.
This refers to allowing UDP port 500/4500 outbound to the mobile gateway of the telco.
Those that are familiar with ports will notice this is IKE/IPSec ports, and yes the phone is making a VPN tunnel dedicated to wifi calling to the telco mobile gateway.
On many networks this is allowed by default, but on others you will need to specifically allow it.
I have seen some hotel wifi blocking this, but generally it works fine.

MVNO shares the same mobile gateway as the MNO :
Singtel - epdg.epc.mnc001.mcc525.pub.3gppnetwork.org
Starhub - epdg.epc.mnc005.mcc525.pub.3gppnetwork.org
Simba - epdg.epc.mnc010.mcc525.pub.3gppnetwork.org
M1 - epdg.mobileone.net.sg

 

[A7997A]

how old is your iphone?

maybe that is a factor?
(on android, anecdotally telcos don't seem to support VoWiFi if older than 3-5 years)

On this front I think iPhone does better than Android phones, iPhone XR from 2018 supports wifi calling well, and even a couple of models before that :

Starhub & M1 states compatibility with iphone 6 or later :
https://www.starhub.com/personal/mo...rvices/wireless-services/voice-over-wifi.html
https://www.m1.com.sg/support/faq/wifi-calling-faq

There is even mention that iPhone 5c supports it overseas.

Samsung flagship phones from 2015 (note 5) is also listed on m1 supported list, but for other models and brands your experience might vary.

 

[froztheart]

just curious. you doing anything to DNS request on your network?

Nope, not touching DNS at all for testing and gotten the previously shared results.

how old is your iphone?

maybe that is a factor?
(on android, anecdotally telcos don't seem to support VoWiFi if older than 3-5 years)

It's an iPhone 13 Pro Max so not that old.

But "older" POCO devices can get VoWIFI though weirdly on the same network.

 

[froztheart]

There is a few factors affecting wifi calling support :

1) Phone support of the Telco.
This is usually implemented in the software update of the phone.
The phone need to have the suitable profile for the telco, it does appears that some component of this can be generic profile, but there are some portion that is telco specific.

2) Telco support of wifi calling :
Starhub have full support even on the MVNO
M1 support on M1/Maxx but not CL. (no confirmation of it working for other M1 MVNO but irrelevant now)
Singtel only has it on the MNO network, none of the MVNO has it.
Simba unofficially supports on Android phones, doesn't work on iPhones.

For phones supported, telco can choose to whitelist/blacklist specific phone models, down to regional models.
If they do this it is usually either specific models that they sell, or year/models that they believe will work.
I suspect SG telco use free for all arrangement : good if it works, too bad if it doesn't.

3) Wifi network support.
This refers to allowing UDP port 500/4500 outbound to the mobile gateway of the telco.
Those that are familiar with ports will notice this is IKE/IPSec ports, and yes the phone is making a VPN tunnel dedicated to wifi calling to the telco mobile gateway.
On many networks this is allowed by default, but on others you will need to specifically allow it.
I have seen some hotel wifi blocking this, but generally it works fine.

MVNO shares the same mobile gateway as the MNO :
Singtel - epdg.epc.mnc001.mcc525.pub.3gppnetwork.org
Starhub - epdg.epc.mnc005.mcc525.pub.3gppnetwork.org
Simba - epdg.epc.mnc010.mcc525.pub.3gppnetwork.org
M1 - epdg.mobileone.net.sg

Just to confirm if I am correct, where to check this ah - "This refers to allowing UDP port 500/4500 outbound to the mobile gateway of the telco"
My IPSec Passthrough is "enabled", anything else I should look at/check for this UDP port 500/4500?

 

[A7997A]

It's an iPhone 13 Pro Max so not that old.

Local set ? IoS version ?

Just to confirm if I am correct, where to check this ah - "This refers to allowing UDP port 500/4500 outbound to the mobile gateway of the telco"
My IPSec Passthrough is "enabled", anything else I should look at/check for this UDP port 500/4500?

This is highly dependent on the router.
But given that it is working on the Poco phone, it is unlikely to be the issue of your problems unless you have highly fine tuned firewall rules in which case you won't be asking this question

 

[Scuderia]

I understand that Singtel WiFi calling have sms enabled too, meaning I can totally turn off cellular signal and still receive sms via WiFi.

What about StarHub and m1?

 

[loganrunning]

It's an iPhone 13 Pro Max so not that old.

ok, that rules out the "old iphone" theory.

 

[froztheart]

Local set ? IoS version ?

This is highly dependent on the router.
But given that it is working on the Poco phone, it is unlikely to be the issue of your problems unless you have highly fine tuned firewall rules in which case you won't be asking this question

Yup, local telco set.

Never tune much, just basics on the router but shouldn't be breaking any that results in this thus, finding it weird that VoWIFI is not working...

 

[loganrunning]

I understand that Singtel WiFi calling have sms enabled too, meaning I can totally turn off cellular signal and still receive sms via WiFi.

What about StarHub and m1?

just tested:
- eight (ie starhub) can receive, can send
- maxx (ie m1) can receive, can send

 

[loganrunning]

Yup, local telco set.

Never tune much, just basics on the router but shouldn't be breaking any that results in this thus, finding it weird that VoWIFI is not working...

yeah, i can't think of any other reason, other than correct profile not loaded at telco backend.

time to talk/email their customer service

 

[A7997A]

I understand that Singtel WiFi calling have sms enabled too, meaning I can totally turn off cellular signal and still receive sms via WiFi.

What about StarHub and m1?

That is a standard feature of wifi calling.
As far as I know all wifi calling implementation supports that.
In fact that is the main reason why I want wifi calling, it is not for calling, but for OTP.

 

[A7997A]

Yup, local telco set.

Never tune much, just basics on the router but shouldn't be breaking any that results in this thus, finding it weird that VoWIFI is not working...

Don't happen to be using original iOS right ?
Factory reset ?

 

[xiaofan]

Stupid question here.

How to confirm an iPhone is working with WiFi calling?

If I cannot see "Wi-Fi" on the status bar on an iPhone 14 with SingTel SIM Only plan, does that mean VoWiFi is not working? Configuration has been done and I can see extra device listed if I also enable the option to allow WiFi calling on other devices.

Apple support article:
https://support.apple.com/en-sg/108066

If Wi-Fi Calling is available, you’ll see "Wi-Fi" in the status bar while viewing Control Centre. Then your calls will use Wi-Fi Calling.

 

[A7997A]

Stupid question here.

How to confirm an iPhone is working with WiFi calling?

If I cannot see "Wi-Fi" on the status bar on an iPhone 14 with SingTel SIM Only plan, does that mean VoWiFi is not working? Configuration has been done and I can see extra device listed if I also enable the option to allow WiFi calling on other devices.

Apple support article:
https://support.apple.com/en-sg/108066

If Wi-Fi Calling is available, you’ll see "Wi-Fi" in the status bar while viewing Control Centre. Then your calls will use Wi-Fi Calling.

It is actually a scrolling "Wi-Fi Calling", if you don't see that, it is not working.
Not sure what you meant by "I can see extra device listed if I also enable the option to allow WiFi calling on other devices."