iPhone 4 3G Call Failed Discussion - Unbiased Technical Discussion Only

Discussion in 'iPhone' started by Desmo1098, Jul 9, 2010.

  1. Desmo1098 macrumors regular


    Aug 28, 2009
    I would like anyone who can add an unbiased technical comment to participate in this thread. I do not want arguments but open discussions about the technical aspects of the dropped call problem. I want this thread to stay on point. Please keep that in mind.*

    I already know I can take the phone back if I do not like it, but I do. Besides, Apple erased multiple posts of mine because they must of not liked what I said. That is why I am here. I am hoping the technical depth and professionalism is much greater here then at the Apple Support Discussion page. Therefore, without further ado...

    Here is the general scenario:

    I love Apple and everything they do. Since I bought my first MacBook Pro and first iPhone my productivity and ability to organize has been increased significantly. Apple's products integrate better than anyone else's. Besides, for the most part I believe they really are intimate in knowing what their customers want. Exclude some of the short responses and general arrogance of Mr. Jobs, obviously he is committed to success.

    I have the iPhone 4 and live in great 3G coverage at least as determined by my iPhone's Signal Indicator. I always have 5 bars, even though there is no field service mode, I am considering the signal-to-noise ratio to be excellent based on Apple's implementation. Again, we have nothing else to go by as of today even though we know publicly Apple admitted there is a problem, and a fix is on the way. To reiterate inside and outside my house I have 5 bars of 3G signal. What I really struggle to understand is why my phone drops calls. That is the fundamental problem, to me anyways. First and foremost I need to make calls, everything else is second in nature.*

    In this more specific scenario I have some specific problems I simply cannot grasp. Here is where I am hoping this place, MacRumors, which has been highly recommend to have great contributors, will adamantly put forth their best unbiased opinions. I have a education in Electrical Engineering so most of this stuff I have a surface understanding of already.

    If I sit outside at a table and have my iPhone on this table with my hands off it, for example using a wired headset, and 5 bars of 3G signal and I still drop calls. I receive a Call Failed message followed by a couple of beeps. Now let's take the following into consideration:

    1. The dropped call responsibility lays on the fault of AT&T and/or Apple's iPhone. We will eliminate, for the sake of this thread, that the drop call had anything to do with the person on the other end, regardless of the service and product they were using.

    2. AT&T uses a implementation of W-CDMA for their 3G network. This opposed to GSM/Edge for their 2G network. Now the 3G side of things utilizes W-CDMA, where it is my understanding that this technology allows more traffic (in the form of data and voice, sine they both use independent channels) without dropping calls. This is where we will need some expertise, but shouldn't the implementation of CDMA allow more calls per base station than TDMA which is what their 2G network is based on? I thought TDMA was designed so that each base station could handle a certain number of "data" and once this threshold was hit, either people are getting dropped or no more "data" is allowed. For the sake of "data" I mean data and calls. I know the CDMA Verizon uses, for example, is designed to allow more calls per base station at the expense of call quality. Once call quality is at a level, designated by the operator, to be unacceptable the call drops. My thought is that these base stations are getting overloaded and just kicking calls off based on signal-to-noise thresholds (i.e. user with iPhone and weakest signal gets dropped; sort of like survival of the fittest if you will). Can someone comment here? Is this whats happening? Why else would a call drop from the iPhone if it has 5 bars of 3G coverage and it is not being held (remember we have eliminated the person on the other end from this scenario).

    Now, if I go inside and create the same setup at my office desk, something else completely different happens. I am still showing 5 bars of 3G coverage, however I cannot place a call, send a text, or transmit data. Furthermore, if I hold the phone the signal indicator still shows 5 bars of 3G. What I have to do is disable 3G to make calls, etc. The real interesting thing here is that once I hold the phone when it is NOT on 3G, for example in the bottom left hand corner, I get the famous signal attenuation until service completely is unavailable as indicating by the signal indictor going from 5 bars of Edge to No Service.

    1. Is it possible we are really dealing with a signal-to-noise ratio issue both on the local base stations and iPhone itself?

    2. Why is it that other handsets from Nokia, RIM, and others do not exhibit this problem. I caution, however, from not saying that they are immune. Because I have tried all of the previously mentioned manufacturers. For the most part the dropped calls while in 3G were non-existent, they certainly were amplified when I was going in and out of 3G and non-3G areas. Which leads to my next point.

    3. How is the implementation of a "hand-off" setup on the device and the base station? Is it possible, Apple, in their infancy have no understanding of "hand-off" on their phone? Again, some expertise here would be good, because I do not know if that is device or base station dependent. It would be a interesting theory however, because as I mentioned it seems that 100% of the time, when on the iPhone, I cam predict when a "hand-off" is coming which in turns tells me I can expect a dropped call. However, not so much as with other phone manufacturers and service providers.

    4. As a side-note, I tested T-Mobile and Verizon. In bother cases using the BlackBerry 9700 and 9630. Now, I know EV-DO is data only, and for the most part the entire country is blanketed in EVDO, but I could tell when I went from a EVDO to 1X area by the clicking in the background while on a call. I ha similar experiences with T-Mobile. What is really interesting here is that on several occasions the BlackBerry 9700 performed a "hand-off" from 3G to GSM/Edge to GPRS effortlessly and with a small percentage of dropped calls. Again, I knew when this happened because the call would cut out for a second and you could hear a click. If you looked at the signal indicator you could see GSM or GPRS.

    5. Therefore, I open it up to discussion, are we dealing with a lack of technical proficiency in the area of "hand-off" between both Apple and AT&T?

    In summation, if you have taken the time to read this, I personally thank you! I hope that I will see this thread grow with great interest because that is where your time is well spent. I look forward to the unbiased ideas and opinions.*

    With best regards,

    (short for the greatest motorcycle in the world ever produced, a Ducati 1098)
  2. diamond.g macrumors 603


    Mar 20, 2007
    AFAIK, Verizon does not do calls with EV-DO, all calls take place over 1xRTT. There was an "update" to EV-DO called EV-DV that would allow voice and data at the same time, but no one used it.

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