04 Jan

VoWifi experience on Jio

Since last week of Nov 2019, I am having serious issues with Airtel at my home. Somehow 4G signal SNR is very poor and most of the calls just fail on that. Airtel support just mentioned that they are putting a new site in my area in Jan 2020 but fail to explain why suddenly it went so bad. I can imagine that support team staff does not have visibility to network in real-time and likely it would be an issue with the 4G antenna on one or more towers. 2G signal was good but latency was extremely high to connect call plus calls still failed regardless (maybe due to high strain on 2G).

So by the end of December, I just gave up and gave the request for porting to Jio. Yesterday my number started on Jio and around 24 hours later I got access to VoWifi which is quite nice. Both Airtel & Jio are rolling our VoWifi but for Airtel, many users have reported it for being locked on Airtel fixed line only.

What is VoWifi?

Well, it’s just native offloading of voice calls over the fixed-line network and is extremely useful for both network operators as well as end-users. Native IP equipment is cheap and it’s way easy to extend cell coverage at home via Wifi instead of proprietary inbuilding solutions. Plus landline was good for quality but form factor and usability was pain. Now VoWifi kind of merges the fixed-line and cell phones and we get best of both worlds.

I think many people confused BSNL Wings with VoWifi. VoWifi is seamless offloading of calls natively while BSNL Wings offered a separate number, an app to run and a separate billing account to maintain with the operator. BSNL Wings was a bad product idea and really awful execution.

Coming to Jio VoWifi, some misc observations:

  1. It’s working for me on the non-Jio fixed-line connection in Haryana circle. I have IAXN (GEPON FTTH) and Siti broadband (DOCSIS 3.0) at home running in active/backup configuration for high availability.
  2. The device has an IPsec tunnel with 49.44.59.XXX. I see isakmp-nat-keep-alive packets every 20 seconds when I do tcpdump on the router.
  3. On my cell phone (which is an Apple iOS device) I see a tunnel is opened on IPSEC1 port. IPSEC2 & IPSEC3 are there for VoLTE.
    IPSEC1 has a link-local IPv6 and an IPv6 from 2405:205:3000::/36 range. The IPv6 on all three IPSEC tunnels is the same as of pdp_ip1 (Cellular data port). I guess that’s probably how they are handing the handovers between VoWifi and VoLTE.
  4. The IPv6 on pdp_ip0 for cellular data is from a different range which again is being announced in the global table as 2409:4051::/36. I wonder why Jio is using publically routable pool for VoLTE and VoWifi. In case of Airtel it a non-routed address space and routes are not announced in the global routing table.
  5. In my test VoWifi to VoLTE was reasonably OK. I tested by shutting off wifi on the cell phone as well as unplugging the cable from wifi AP to test. In both cases call went silent for 1-2 seconds and resumed over VoLTE. It did not come back on VoWifi once Wifi was back live.
  6. Latency from both connections to other endpoint (the router before the IPSEC endpoint) is around 60ms. Either the endpoint is somewhere far off or (more likely) it’s a case of not-so-good routing between Airtel (upstream of my ISP) and Jio.
  7. There’s a quite noticeable improvement in connection time. For IVR based numbers it’s close to 2-3 seconds. Which is a great improvement for someone like me who was on 2G non-VoLTE calls for December!

How to check interfaces and routing table on your phone?

Well use HE.NET Network App on Android or Apple iPhone and you will be able to check that!

That’s about it. Back to the world of routing. 🙂

07 Jul

Indian telecom voice market and updates


 
Suddenly the voice market in India is becoming very interesting. Earlier it was the case of Jio (and competitors) launching unlimited voice plans and now it’s the case of Govt. of India permitting IP telephony.
IP Telephony i.e networks where telephony happens over IP (not to be confused with IP to IP calls but) where IP to PSTN interconnects happen. Till a few months ago IP telephony (or IP-PSTN) interconnection was allowed only under certain conditions like doing it inside a building only for purpose of call centres (with OSP license) or running SIP trunks over private networks. Things like termination of calls originated from the apps was not allowed (where IP-PSTN was happening within India) as well as DID or Direct Inward Dialing numbers were not allowed. There were even cases where apps/businesses had to shut down due to confusing regulation. Here’s a nice article from Medianama about it. But all those were things of past.
In May Wifi calling or calls via Wifi where wifi is used loosely and it’s essentially called via any sort of Internet connections were permitted (news here). Later after TRAI’s clarification it now has been formally allowed. While it may not look as attractive as it should have been in the age of WhatsApp calling (IP to IP, not PSTN mess involved!), it still is quite interesting and going to bring some major change.
 
Here some of the upcoming things we all can expect to see in the next few months:

  1. All key operators will launch native wifi call offload for flagship phones (Google Pixel, iPhone, Samsung Galaxy’s etc). This will offload a hell lot of voice traffic from the cell towards home wifi. Various fixed wired ISPs would now be carrying a significant chunk of voice traffic.
  2. All key operators will launch an app for making phone calls and it would not only be for their users but also for other users. So while at this point one has to have a SIM card from the provider, next it would be sim card as well as “virtual connection” in form of a sort of KYC followed by an app essentially making use of SIP for call routing.
  3. SIP trunks over IP networks will become common and that would be huge. In present times if someone needed 5-10 connections for official use with call haunting etc, it was either POTS analogue phones or PRIs (yuck!) or SIP trunks running over the private network. Going forward now it would be SIP trunks offered over the regular internet all would be facilitated via closed systems (apps and portals) as well as open systems based on SIP. This would help significantly to businesses which have direct customer interaction.
  4. Market of DIDs or 10 digit virtual phone numbers will become very common. Telcos would be offering it directly and various platforms like Microsoft’s Skype, Google Voice, Vonage etc would also join in and resell those.

 
An interesting case of above is BSNL’s recent announcement of their platform “Wings”. Though based on their usual track record of totally screwing up, I would keep my expectations low, but still offering seems interesting and gives an idea of the updated regulatory framework.