Airtel 4g not getting sms OTP with Vowifi

[bigbyte.me]

Jio gets normal as well as OTP sms on vowifi without any mobile network. With Airtel you need to get actual Mobile network before you can receive SMS.
outgoing sms on voWiFi works fine with both providers.

 

[igloo]

outgoing sms is also not working here.
yet to receive sms sent at 5pm

 

[panks21]

No issues on Airtel here.. Was on Galaxy Note 10+ earlier. Now on iPhone 12
30 mins ago made an online payment

 

[Aakash Malhotra]

wait, so can you also get sms if you're mobile signal is 0 and vowifi is on ?
I don't think it works.

 

[panks21]

I didn't mean that. If your mobile signal is 0, you cant get onto vowifi either as the SIM first authentication happens through mobile network and post that you get authorization from the operator that you are allowed to use vowifi. This is the reason vowifi doesn't work when roaming outside India without proper authorization from your service provider

 

[ijsa]

Source


Here you can see that there is 0 signal in Sim 2 that is Airtel... VoWiFi is working but incoming SMS will not work.

 

[pillaicha]

Did anyone raising the issue? Maybe through their app or otherwise through Twitter? Email?

 

[panks21]

@ijsa
Thanks, I stand corrected. I posted that based on my understanding few years ago. Looks like things have improved

 

[pillaicha]

I've noticed my network has to change to 2G from 4G in order to send or receive sms. So I think Airtel's implementation of IMS stack is restricted only to voice and not sms. IMS stack is what enables devices to use volte, vilte, vowifi, etc. So SMS still relies on 2G to get around. Also authentication with Airtel's IMS core occurs over IP. It is upto the telecom carrier how this authentication process happens. Maybe Airtel had implemented the use of regular Airtel 4G for primary authentication for IMS, so only after that happens will vowifi and volte will work? Mind you, you can switch off data services but IMS stack of your phone can still use your phones data to connect to its server.

Jio on the other hand is using all IMS core. They obviously can't afford not to cos they don't have any other network than IP-only 4G. So maybe their authentication can happen without needing regular 4G to be available. This probably is the reason for being able to use all IMS services despite being on wifi.

 

[ijsa]

But we can send successfully SMS on VoWifi.... And what I have noticed that in case of OTP, it's received as soon we step outdoors and get any network, not just 2G.