Sorry for replying to myself endlessly, but one thing I'm unclear on is voice and text on mobile networks, in light of IP Daley's report of services during a weather event.
Specifically, are talk and text considered VOIP, or "regular" talk; SMS network or data?
Now granted, I can't speak with definitive authority, but a reasonable educated guess can be made given the dearth of what I do know. I imagine with Google's implementation and the pricing structure that mobile voice and SMS are not data based but traditional GSM voice service, so they should take precedence over all mobile data on towers. Most likely given Google's affinity for standards (when it's to their benefit), the GSM/WiFi handoff is just the same 3GPP UMA/GAN implementation I mentioned from 2005 that T-Mobile's been using all these years. This would mean that WiFi call termination on the Fi user end is probably still being routed through T-Mobile (as Sprint is only a 4G LTE roaming partner) instead of Google like traditional Hangouts would be. This also explains the fixed baseline price of $20/month for "unlimited" talk and text, as even over WiFi, the last leg of call routing is still being handled through T-Mobile. All this said... as an MVNO, they will still be third priority in the pecking order on the physical towers themselves. That pecking order from what I understand is as follows:
Voice first, SMS second, data third... though due to the nature of tower loads, SMS is the most reliable under heavy loads due to it not being real-time data critical.
In this data usage hierarchy, network services are prioritized postpaid first, prepaid/partner roaming second, wholesale/MVNO third.
Only one thing trumps all on a tower: first responder accounts.
Under normal situations, you'll probably never tell the difference with regular mobile voice calling even on heavier loaded towers, but under regional emergency conditions, the pecking order doesn't matter as much because once the towers are saturated,
everyone is screwed. That said, even postpaid data will get throttled/disabled long before wholesale voice does. This is why I say mVoIP is such a bad idea - data's always the first to go on a busy tower, sufficiently high speed mobile data for mVoIP doesn't have the network footprint that traditional voice does, and those two reasons effectively make it less reliable and wholly inappropriate for people who actually
need mobile phone service.
But back to Fi, T-Mobile, Sprint and the case for 3GPP UMA/GAN. Remember, Google has partner agreements with Sprint and T-Mobile with GV integration into their networks. In hindsight with the rollout of Fi, it makes perfect sense that these two carriers have integrated network trunking agreements with Google's VoIP network. T-Mobile has a history of SIP trunking, Sprint's had semi-public SIP trunking with their mobile network for years, and I even remember back in 2008 being able to make free SIP-to-Sprint phone calls... and a tumbler just fell into place.
Now, I will admit a misunderstanding on my own in the past and correct myself again regarding Republic. My original understanding from the Defy XT days still stands that they're mostly just using VoIP, call forwarding and mobile voice services. I had figured that given 3GPP2's (yes, I know it's confusing) CDMA2000 standard doesn't have anything that I know of along the lines of UMA/GAN for voice services, and after they launched their proprietary Moto X, I suspected they were doing 100% mVoIP. It probably still is some cludgy mVoIP for WiFi to tower handoff in most instances (especially for the call quality dropoff after the transition to mobile) and they might be leveraging some level of Sprint's SIP trunking back-end, but I've seen enough reports to know they still need and use a hidden second number and the CDMA voice network. This is likely given there's still considerable mobile data access and usage on the $10 plan. This should remain a concern, by the way, especially with their $10 "unlimited" talk and text plans. It probably routes mVoIP whenever possible, and if data connectivity is insufficient, fails over to the voice network when it can't. Remember, their old "beta" mobile usage restrictions back in 2011 used to be as low as 550 minutes and 150 texts without sufficient WiFi usage on a $20/month plan. People make a huge stink about the data and how the $500+ ToS penalty won't kick in before 5GB of data and the one time "free pass", but nowhere is there a disclosure about
what constitutes mobile voice usage abuse.
...but back on topic. This really is why I don't recommend 100% mVoIP solutions like FreedomPop, TextNow, or getting T-Mobile's $30 5GB plan and violating their ToS by using a VoIP client over it. As for that concern with Google Fi? I don't think that concern applies here. A lot can be understood through the price structure of an MVNO, especially when you toss international roaming into the picture. For all intents and purposes, it looks like Fi phone termination isn't SIP/VoIP, but UMA/GAN. If this is the case, they'll get a higher pecking order on any mobile towers than the mVoIP providers would under peak load.
