Unlocked SE cell without gsm850 on cingular

June 6, 2007 8:23 PM

Bought a SE Z310i. Didn't realize it does not have gsm850. From research I've done cingular around Dallas uses 850 and 1900. The 1900 signal is uberflakey. The company I bought from told me something that I do not believe.

First they are in California, so I don't think they really know what is happening here around Dallas. They suggested going to a local cingular store and request a new/replacement sim card. He says they will do it for free, and that US carriers are starting to use band 900 so the new sim will improve performance. Again he is in Cali not Dallas. Can a sim card somehow "activate/utilize" the 900 band that my less than a year old sim card is not doing? Another thing I have been told/read again and again is cingular will not support a phone model they do not carry/offer, which the Z310 they do not.
Here is description of signal problem: extremely weak in the same spot that my quad band is full bars. When signal drops the phone will not auto search even though it is set to auto search. I have to off/on to search and pick up signal.

posted by girlbowler to technology (8 comments total)

The guy at the company is an idiot. No carrier can in the US can use the 900Mhz spectrum on mobile phones. The FCC gave it to cordless phones and baby monitors and other unlicensed applications. If your phone doesn't have 900Mhz the SIM card won't change that.

The only thing he's right about is they will give you a new SIM card if your old one isn't working -- or is really old and doesn't have 3G mojo on it. But your phone doesn't have that feature.

If your quadband is working well, you're probably in an 850 area. you can either move, switch to T-mobile as it doesn't use 850 that much [I haven't found a place where I can't use my 900/1800/1900 triband SE phone], or sell the phone on ebay if the guy in California won't accept the return.
posted by birdherder at 8:33 PM on June 6, 2007

Thank you, birdherder.
Sorry, I should have mentioned the Z310i is a triband 900,1800,1900 phone. My sim does have 3G on it.
I did look up cingular coverage on gsmworld maps
gsm 850
gsm 1900
3G 850/1900 + GSM
Now I'm a bit confused by 3G vs GSM.
posted by girlbowler at 9:10 PM on June 6, 2007

The 3G technology is overlaid with GSM. GSM is the telephone voice and SMS standard. GPRS integrates with GSM to provide packet data. EDGE is enhanced GPRS. The 3G technologies, however, aren't quite as intertwined with GSM (voice) as the others. That's why it gets its own entry.
posted by jeversol at 9:44 PM on June 6, 2007

Thank you, jeversol.
That is a very nice and clear description.
My W600i is the quad band and it has EDGE.
The Z310i is a tri band with GPRS.
posted by girlbowler at 9:54 PM on June 6, 2007

3G [UMTS] is on the 1900 and 2100 bands. My SE phone has 3G on the 2100 band which doesn't work here since ATT is using 1900 and T-Mobile is using a slightly different band so my phone that I could roam with 3G in Japan, Germany and UK won't ever work in the US.

Your phone doesn't have any flavor of 3G. The only 3G phones that will work in the US are the handful that ATT is selling. All of the 3G branding phones imported from Europe will work everywhere but here.

Eventually "worldphones" will need to be quadband GSM and triband 3G to truly work everywhere.

Maybe in the future the FCC will harmonize the frequencies with the rest of the world to simplify things, but I'm not holding my breath.
posted by birdherder at 10:02 PM on June 6, 2007

There's no such thing as an "850" band. It's referred to as the 800 MHz band.

As mentioned, the 900 MHz band is not licensed for cellular use in the US. Neither is the 1800 MHz band. Those are used in Europe, but probably won't ever be used here; that spectrum has been allocated for other uses in North America.

The officiating authority is known as "The Office of Spectrum Management". (This PDF file shows all of the licensed spectrum, and then some. Here's the info in text form.)

"GSM" refers to "Global Standard for Mobile Communications". It's a "second generation" standard based on a TDMA air interface. Over the course of about ten years of competition it's become blatantly obvious to everyone in the industry that the CDMA approach to an air interface is vastly superior, and the GSM committee finally bit the bullet and designed a "third generation" (i.e. 3G) standard. It isn't known as "GSM". It's called "UMTS" "Universal Mobile Telecommunication System" and it uses a CDMA air interface. (Their version of CDMA is referred to as "W-CDMA".)

Once GSM got established, and then had to compete against IS-95, one of the competitive problems that developed was that GSM as designed couldn't provide its users more than 19.2 kilobaud of digital link. Meanwhile, IS-95 initially offered 56 kilobaud, and later even higher rates. Because of the way GSM was designed, there wasn't any way to increase it, so they designed something entirely new for digital. They called it GPRS, "General Packet Radio Service".

GSM, GPRS, and UMTS are all mutually incompatible and cannot occupy the same spectrum. For GSM operators to start offering higher speed digital, they had to clear spectrum, stop using it for GSM, and dedicate it to GPRS. Mostly that hasn't been very popular (with the operators) because it reduced the amount of voice traffic they could carry.

And when the GSM operators finally upgrade to UMTS, they'll either have to license new spectrum for it (which is what they did in Europe) or clear existing spectrum by reducing the capacity of their existing GSM systems.

Jeversol says "the 3G technology is overlaid with GSM". Yes and no. What they did was to maintain compatibility with the higher level protocols that GSM used, but completely rip out the low level TDMA air interface and replace it with the W-CDMA air interface. However, even at the higher level compatibility is only partial, because part of what they wanted to do was offer new features that couldn't be supported by GSM's TDMA air interface. (Like video.)
posted by Steven C. Den Beste at 10:12 PM on June 6, 2007

Your phone is designed for Europeans who travel to the US. It will work well in Europe. In the US, it depends upon the provision of the 'legacy' GSM 1900 service.

In 2002, AT&T and Cingular decided to start offering GSM 850. Cingular's expansion has favoured GSM 850 over GSM 1900. Your phone doesn't handle GSM 850.

So, your guy in Cali is bullshitting you, and birdherder's options are accurate.

My phone, brought over from the UK, is an old 800/1800/1900 triband and occasionally loses a Cingular signal and roams to another network provider.
posted by holgate at 10:35 PM on June 6, 2007

Thank you all for your answers and information.
posted by girlbowler at 8:09 AM on June 7, 2007