iOS 8: T-Mobile WiFi Calling on 5s issues

@muadible2010: The more I think about it, I highly doubt T-Mo would "pull back" the availability of WiFi calling. It has been available since Beta 3 of iOS8.

I suppose anything is possible, and maybe they did find a show-stopping bug, but I at this point, I am not sure the front line support staff at either Apple or T-Mo really know anything about this feature. The available date of 9/25 makes coincides with the day T-Mo starts shipping the WiFi Cellspot routers, so that leads me to believe many at T-Mo do not realize that you don't have to have their router in order for WiFi calling to work. I think they are jumping to a conclusion there.

I am heading to the Apple Store this evening to discuss this with a Genius, but my original conclusion remains. I think it is highly dependent on how you obtain your WiFi Internet connection, and devices that are more "promiscuous" will basically allow any and all traffic in and out, and the key to this whole thing is getting Apple and/or T-Mo to document and disclose the TCP/UDP/ICMP details required.

My own testing bears this out. I can't get it to work on WiFi behind a Cisco ASA-5510 firewall, but it does seem to work when I join the 5s to a Verizon MiFi hotspot device. This seems consistent with what others have explained. For those of you who can't seem to get it to work, PLEASE try it on other WiFi networks.

I just wish that iOS 8 would positively announce or display when a WiFi call was placed or was in progress. The indicators are non-existent as far as I can tell. My own Samsung Galaxy Note 3 running Android 4.4.2 is very good about this. It specifically tells you when calls will go out over WiFi, etc.

I guess if push comes to shove, I will set up a network traffic analyzer (I have been wanting to learn how to do this on my home LAN anyway) and isolate the IP address assigned to the 5s and see what kind of chatter it generates...

Here is the latest update from last night's visit to the Apple Store:

Spoke to a Genius and she did some checking, and did a rather interesting test. She put the phone into Airplane mode, and then just turned back on WiFi only, leaving off the cellular radio.

We then placed a test call there in the store from my phone to the 5s. It worked. This proves to me that the feature definitely works, and appears to be properly configured on the phone and T-Mobile's back end. The phone does have Carrier Update v17.1 - but I also was having trouble finding the switch in settings to specifically enable WiFi calling, so perhaps the carrier update removed that switch? It is either that or I am not looking in the right place. For those who can still see it, exactly what are the steps to get there so I can check to see if it has been pulled from mine due to the carrier update?

So, after leaving the Apple store, I then went home to try this same test on my home LAN/WiFi that has the Cisco Firewall at the border. I put the phone into Airplane mode again, and then just turned on the WiFi radio only, leaving the cellular radio off. Much to my surprise, the WiFi call worked there as well.

This tells me that my theory on the TCP/UDP ports was probably incorrect. I made no further changes to the firewall, and the 5s appears to have used the available open ports just like my Android phones do. In one sense, this is good because it tells me more specific firewall rule changes are apparently not necessary.

However, this is bad because it then tells me that there must be issues with the algorithm that Apple/T-Mo use on the phone to determine when a call is made or taken which radio to use. It seems to me that under iOS 8.0 and the current carrier settings the phone must be set to prefer a weak cell signal over even a strong WiFi signal. I can't think of any other explanation, because if the cellular radio is unavailable, the WiFi calls are pristine and seem to work well.

At this point, my wife has a workaround, but it is a huge pain. She has to remember to put the phone into Airplane mode when she gets home, and turn it off when she leaves the house. I sincerely hope that future iOS 8.x and/or carrier updates address this and set the phone to either ignore the cellular radio for calls for Wifi, or use it only after an attempt of a WiFi call fails.

@muadible2010: Thanks for your update. Based on your environment, I'd say you made the right call. That cellspot router they are offering is a very capable 802.11ac router in its own right (rebranded late model Asus running custom firmware that prioritizes calling traffic so that streaming won't kill a call). For my home network, it is not that easy. I am extremely particular about my hardware, and the reliability and stability of Cisco hardware is very important to me. It sometimes comes at the cost of flexibility until I get rules correct when required, but I prefer having my WiFi access points separate from my firewall/routing device. It is good to see in this case that it does not appear further tweaking will be required.

So, I am taking a different approach with T-Mobile. I am going to refuse the delivery of their cellspot wifi router when it arrives and instead accept the delivery of the new LTE booster they also shipped. Their (native) signal strength in my home (prior to any augmentation) is terrible. I currently have their 3G booster and it helps a little bit, but they promise me the performance improvements with the LTE version are quite substantial. I am eager to try it when it arrives.

@yummymayo: Your experiences perfectly mirror my own. I also firmly believe that as of right now the phone does get confused on which to use, which explains why my wife's calls drop left and right at home, despite having a strong WiFi signal throughout the house. I think the (very) weak cell signal trumps right now, and Apple needs to add some sort of option to specify how WiFi calling is handled, beyond the feature just being on or off. Somewhat akin to the feature setting they have for how iOS handles iMessage if you are familiar with that. Sometimes, you can have problems with message delivery, and there is a setting to send a message as a traditional SMS message if iMessage fails. I think a similar approach is required here. I would much prefer settings that afford granular control over how calls are handled. Profile settings based on location (like I have in Android) would be IDEAL, but that is probably a pipe dream for iOS because it is supposed to "just work".

I see iOS 8.0.1 was rolled out this afternoon, so all bets are now officially off. There was no specific mention of WiFi calling improvements in the release notes, but Apple is notorious for implementing changes well beyond what they document, so it would not at all surprise me if something was changed behind the scenes or another switch has appeared. I will probably upgrade hers tonight (since its hers... <grin>).

Beyond the WiFi issue, my only other complaint is the battery life, but I know that is another topic for another day....