Sent to you by Brent via Google Reader: Verizon and Sprint iPhone 4S
and the limitations of CDMA via TiPb - The #1 iPhone, iPad, and iPod
touch blog by Rene Ritchie on 10/8/11
iPhone 4S is the first iPhone to have both Verizon and Sprint CDMA
versions available alongside the AT&T GSM version. CDMA is famous for
its rock solid reliability and call quality and now that iPhone 4S is a
world phone, it can even roam on international GSM network. However,
CDMA brings with it some downsides as well, including lack of
simultaneous voice and data over 3G, subtle quirks to SMS, and greatly
reduced conference call options.
None of these are unique to iPhone 4S on Verizon or Sprint, but they're
something to keep in mind if you're thinking of switching to one of
those networks now that they have iPhone 4S.
So here's the deal.
There are some great advantages to CDMA. It tends to need less towers
to cover greater areas so CDMA networks typically have better reception
in more places. This also means they tend to sound better, more often
for voice calls. If you use your iPhone as a phone — who knew? — and
that's the most important thing to you, or if Verizon or Sprint provide
the only reliable coverage in your area, than case closed.
If cost is a factor, well we've already put together that breakdown for
you.
- AT&T vs. Verizon vs. Sprint: Which iPhone 4S should you choose?
But if you want to know what you're getting into when it comes to the
data and conference calling tradeoffs, there are several things to
consider.
Note: We'll be using a lot of tech terms, so see our wireless
networking guide for more on what all these acronyms mean.
Slower 3G data
iPhone 4S on AT&T and other GSM networks supports 14.4 Mbps HSPA+
download speeds. Depending on where you live, you may never get
anywhere near that speed in the real world, but the potential is there.
By contrast, while CDMA-2000 give Verizon and Sprint great voice, their
EV-DO rev A 3G data speeds are theoretically limited to about 3.1 Mbps.
No simultaneous voice and data
Verizon and Sprint's EV-DO Rev. A network does not support simultaneous
voice and data the way HSPA and HSPA+ does for AT&T (and other GSM
carriers).
That means if a call comes in while you're using 3G data — surfing the
web, Skyping, sharing your connection via personal hotspot — you can
either ignore the call and continue using 3G data, or answer the call
and effectively put your 3G data connection on "pause". If you're on a
call you won't receive email or push notifications and if you try to
surf the web or download an app you'll be informed you're not connected
to the 3G network. Once the call ends, 3G data reconnects and you can
start using the internet again.
If you're on Wi-Fi as opposed to 3G data you can make calls and use
data without a problem. It's only 3G data that cuts out during calls.
Verizon and Sprint have chosen not to roll out EV-DO Rev. B, which does
support simultaneous data in favor of more quickly deploying a 4G LTE
network (currently a hybrid CDMA-voice with LTE-data network, in the
future a Voice over LTE network) and WiMax with LTE to follow,
respectively. There are some phones that support Voice over Rev A
(VoRA) aka SVDO which will allow for simultaneous voice and data on
CDMA/EV-DO phones, but not the Verizon or Sprint iPhone. (See The Cell
Phone Junky for more on the technology.)
SMS/Text splitting
SMS/Text messages are limited to 160 characters. On AT&T and other GSM
iPhones, if a message exceeds 160 characters it will still be shown as
a single message to both the sender and receiver. On Verizon once an
SMS hits 160 characters, any additional text is split off into a second
message, after 320, a third message, etc. The same content is still
delivered, it's just not presented as nicely. (In some cases the
message parts might even appear out of order which is even more
annoying.) Some users claim to seldom if ever experience this problem
in the real world, others say it happens often enough to annoy them.
Limited conference calling
Verizon and Sprint's CDMA networks only supports "3 way calling" so you
can only enter into a conference call with up to 2 other people (3
including yourself) at the same time. It doesn't matter if iPhone can
handle more, CSMA networks and hence the Verizon and Sprint iPhone is
limited to 3-way calling.
Likewise, handling conference calls is also more challenging on the
CDMA iPhones since you can't take one party "private" or hang up on one
caller while keeping the other active. You can only hang up on all of
them at once.
Apple provides the following diagram in their knowledge base:
The network
So yes, overall there are a lot of limitations to the way CDMA handles
voice. However, if Verizon or Sprint has great coverage in your area,
you're on Wi-Fi when you want to talk and surf, split SMS/Text messages
rarely happen or don't bother you, and agile conference calling isn't a
must-have business feature for your iPhone, you may not care.
Otherwise it's a compromise. Decide what's most important to you and
which carrier best provides it. If anything is a deal-breaker, then
that makes your choice much simpler.
For more information and help check out our iPhone 4S Forum.
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