Resolving problems with Airtel VoWiFi, WiFi Calling

Disclaimer - this is one possible solution, for a specific scenario. This post does not aim to resolve all possible WiFi Calling issues.
Posting this here for people who have been trying to resolve issues with WiFi calling not working on Airtel, it took me a really long while to figure this out.

Problem: Handset is configured correctly for WiFi Calling, have Airtel v-fiber/xtream broadband at home. Handset does not show the VoWiFi icon at home, but shows the icon when I visit a friend. ViWiFi does not work over my own Airtel home broadband, but works with someone else's Airtel broadband.
Solution TL;DR: Check router DNS settings

Details:
VoWiFi was launched and I was could enable the settiing on my iPhone 7, however the VoWiFi indication (network name changes to AirTel WiFi on an iPhone) never showed up on my mobile handset. In the interim, i visited a friend who has AirTel broadband too, and on connecting to his home internet, VoWiFi showed up as active. Did my research online, found that my home router might not be allowing traffic on UDP ports 4500 and port 500. Experimented with my router, set up port forwarding rules, and still couldnt get WiFi calling to work. Called Airtel moble customer care and Airtel broadband customer care, got passed from department to department with no luck, spent several minutes on multiple occasions with customer care and got fed up. Was told by customer care executives that there is no option on their CRM software to register complaints for WiFi calling, they remotely checked my router and found everything to be set up correctly too.

The Solution:
Randomly while browsing forums where people reported such issues with T-Mobile and Verizon, I chanced upon a post which set my head ticking. I remember having changed the DNS servers configured on the home router a few years ago. I had changed the primary and secondary DNS servers from the default Airtel provided DNS server addresses to Google DNS (8.8.8.8, 8.8.4.4). I called up customer care, got Airtel's primary and secondary DNS server addresses for vFiber in New Delhi (202.56.215.54, 202.56.215.55) restarted my router, disabled and re-enabled Wifi calling on my mobile phone and restarted that too for good measure..
.... and voila VoWiFi!!

I guess for this particular scenario, the issue would be automatically resolved when Airtel opens up WiFi calling to other ISPs because apparently as of now in my area only their own DNS servers are able to look up the Wifi Calling servers. Hope this post helps someone else too.
 

popcorn

Senior Member
Messages
3,303
Location
Mumbai
ISP
One Broadband(15mbps) & MTNL 600 Combo(12mbps)
Airtel uses a ip address starting with 117.x.x.x something... I had done the research a while ago and had the exact IP address/range. It uses 4500 port which is IP Sec protocol. Infact it is also same with JIO. Jio used 47.x.x.x or 49.x.x.x something ip. I had exact IP address if anyone wants.
It has no relation to public dns and ISP dns. the vowifi will work if your firewall allows ipsec protocol UDP 4500. In most routers it is enabled by default along with all VPN based services.
 
Messages
1
Location
NA
ISP
Airtel
Hi, i had forwarded the UDP port 4500 and it was working fine until a week back or so. it has since stopped working for jio vowifi for some reason. has there been a change on the backend from jio itself?
 
Messages
1
Location
Bangalore, India
ISP
ACT Fibernet
Jio responds with a dummy IPSEC server outside it's whitelisted ISPs. So does Airtel, possibly to prevent VoWifi calls when on international roaming. Querying epdg.epc.mnc861.mcc405.pub.3gppnetwork.org (this is for Jio) will give you some random blackhole IP which will fail to connect. Change to your ISP's DNS and everything will work as the ISP's DNS has the correct entries. WTF!

But my ISP's DNS is shitty, super-slow. I only have a choice between dropping calls or good internet

Current Jio ePDG gateways are 49.44.59.36 and 49.44.59.38

I'm exploring adding these entries to my router's host file.

You can do the same for Airtel, just find its mnc and mcc code and replace it in the above DNS query
 

cochin007

Newbie
Messages
100
Location
NA
ISP
vonage
I am in uk and have a JIO sim. But vowifi option is not showing. Is it because the connected network is 3G while roaming. The phone shows same option for EE which has Vowifi option but doesnt get enabled for Jio?
 
Messages
87
Location
India
ISP
Multi ISP
Will VoWiFi work between Airtel-SIM iPhone and Airtel's own 4G Hotspot? It used to a few months ago, but has stopped working since. It now works Airtel to Other, not Airtel to Airtel. Any suggestions, please?
 
Messages
3
Location
Bangalore
ISP
ACT
Strange issue!! o_O I have iPhone 11 pro with Airtel 4g sim in Karnataka circle, I have been using wifi calling happily, however, suddenly from last month, I observe this - When I restart or flip my phone from airplane mode, Airtel wifi shows up for around 30 secs and then it switches back to Airtel and loses the wifi calling. Did anyone face a similar issue? Any help appreciated.

I am using ACT broadband and there has been no change as such in internet connection from my side.
Trying with another JIO sim on the same ACT wifi works seamlessly on the same iPhone.

I see that there are datapath entries in my router on port 4500 and destination as 106.200.64.1 which seems to match as per @rajil.s post above.
Also tried using different DNS such as Google, OpenDNS, Cloudflare, and ACT native DNS, all give the same result.

P.S> As usual airtel cust care is clueless and asks me to change SIM or turn the option in settings, which both are fine and to even make sure, I replaced my SIM and the issue has been there even after that. :rolleyes:
 
Messages
3
Location
Bangalore
ISP
ACT
Thanks, @Sushubh for pointing to that thread. That is pretty weird, vo-wifi is helping reduce their network load, why would they make it a premium service for platinum plan users!! :unsure:

BTW, I am a prepaid user with a 379 plan.

However, what I observe is -
When I connect to a hotspot connection from JIO prepaid sim or even a Vodafone sim network, Airtel vo-wifi works seemlessly! :ROFLMAO:
Only when I am connected to my home ACT broadband wifi, the Airtel vo-wifi does not work (or as I mentioned in the above post - it disconnects after 20-30 secs).

Would that mean, it is something to do with my home ACT broadband? :rolleyes:
 
Messages
461
Location
Lucknow
ISP
BSNL
Did you try setting up your phone cell network to 3g instead of LTE?

Once i did that vowifi became 100% stable. Once i step outside the house i change back to LTE.