[HD2 General] Agoattamer:
It is a difficult topic to explain. GSM actually includes WCDMA and UMTS. Selecting WCDMA actually narrows down where on the band to look for your signal.

GSM – Global System for Mobile communications: GSM is the most popular family of mobile network standards in the world. Most prevalent in Europe, Asia, and other parts of the world, GSM systems include GPRS, EDGE, WCDMA or UMTS, and HSDPA. GSM transmission speeds can range from less than 40 Kbps (for the first version of GSM, or 2G) to 1.1 Mbps (for HSDPA, or Advanced 3G).

UMTS – Universal Mobile Telecommunications System, also know as WCDMA: A 3G and Advanced 3G mobile communications technology. UMTS incorporates both W-CDMA and GSM standards for communications, and was designed as the 3G successor to GSM. It enables very high-speed data transfer for data-intensive applications. Transmission rates range from 550 Kbps to 1.1 Mbps.

HSPA – High-Speed Packet Access: A collection of mobile telephony protocols that extend and improve the performance of existing UMTS protocols. Two standards, HSDPA and HSUPA, have been established and a further standard, HSOPA, is being proposed. The two existing standards (HSDPA and HSUPA) in the family provide increased performance by using improved modulation schemes and by refining the protocols by which handsets and base stations communicate. These improvements lead to a better utilization of the existing radio bandwidth provided by UMTS. Typical download speeds are 550 Kbps to 1.1Mbps.

As you can see, it is quite confusing as all three are related. Right now I am trying to avoid all this switching. And with WCDMA selected I do not see G or E on my phone anymore. Now if you were in an area without the 850UMTS band (no 3G or H(3G+) then I believe you might want to select GSM. If unsure then leave auto selected but phone will keep scanning the bands and I believe this is one of the reasons for seeing the random G, E, 3G, or H(3G+) and a reason for the data lockups if you get them.

Now down below is a little different. That picks out the separate bands. I use a non telstra rom so the menu will be different from the telstra rom. Does this make a difference? I dont believe so. This is just a menu and the first on the list will pick setting one of the radio. The only differences is the 900 to 850 swap.

radio setting........Telstra...................................Unbranded rom

1........................auto..............................................auto

2........GSM(900+1800)+UMTS(2100).............GSM(900+1800)+UMTS(2100+900)

3...........GSM(1900)+UMTS(850)...........................GSM(1900+850)

4.........................NA........................................UMTS(2100+900)

5..........GSM(900+1800)+UMTS(850+2100)......................NA

6.............GSM(900+1800)+UMTS(850)...........................NA

So setting 1 is the same. Auto. Searching of all the bands. Dont want that.

Setting 2 in either case does not include the 850 band. No to this one.

Setting 3 just adds the 850 band in and keeps the 1900 band. Both of which ATT uses. The unbranded rom doesnt list 850UMTS because its physical radio doesnt include this. This is the one I have selected.

Setting 4 looks good but with the T9193 I have no signal at all.

And setting 5 and 6 cannot be selected with the unbranded rom.

So the only 2 selections that work for the unbranded rom are setting 1 auto and setting 3. On Auto my phone is on H most of the time. On setting 3 it sits idle on 3G and when the data connection is open it switches to H. Now which is better? Not sure on that 1 yet. I have had no lockups on setting 1 in 3 days. I just switched to setting 3 to try for a few days. As long as it doesnt lock up I will keep this setting. H requires more power than 3G to stay connected. So I am thinking I will gain bettery battery life on setting 3.

When I get a definite response from kevin on the exact registry layout for the telstra menu I am going to make a cab and switch my menu to look like the telstra menu. I am guessing that it will make the menu look like the telstra rom but the settings will actually be the same for the radio. I will at least be able to select setting 5 and see if it does anything or crashes my phone. lol.

Sorry for the long post but there is much info here.