How do I find the call frequency?

[Esteban]

Does any know how to tell which frequency (800 or 1900) the phone is using when calling from a particular location? I live in a remote fringe area, where reception varies from 0 to 3 bars and dropped calls are the norm. I'm looking into a remote antenna, but they are frequency specific.    

[gakido46]

I think most remote area calls are 850.

[MikeDez]

It varies from area to area, and network to network. You can use the engineering mode screen to get exact info. To do this go to your dialpad and dial 277634#*# when the phone test menu opens go to Modem Settings and select Engineer Mode. Now a yellow box will pop up and say PS. . <ST:08> . .UI at the top (this is the page you need to be on). Look for UARFCN and a number, that number is the channel being used.

Here is a list of channels 4357 - 4458 and 1007, 1012, 1032, 1037, 1062, 1087 are WCDMA 850.

Channels 9662 - 9938 and 412, 437, 462, 487, 512, 537, 562, 587, 612, 637, 662, 687 are WCDMA 1900.

Also you can use the following formulas to determine the center frequency of a particular channel:

850 Channels:
Channels 4357 - 4458
Divide channel number by 5 (i.e. 4384 = 876.8 MHz)

Channels 1007, 1012, 1032, 1037, 1062, 1087 (850):
Divide the channel number by 5 and add 670.1 (i.e. 1007 = 871.5 MHz)

1900 Channels:
Channels 9662 - 9938:
Divide channel number by 5 (9662 = 1932.4 MHz)

Channels 412, 437, 462, 487, 512, 537, 562, 587, 612, 637, 662, 687 (1900):
Divide the channel number by 5 and add 1850.1 (i.e. 412 = 1932.5 MHz)

Now you can press the camera button for 3 seconds to make the yellow box go away. I hope this helps you.

[Esteban]

What a great detailed response! Thanks.

I had already discovered the engineering mode but didn't know how to interpret the UARFCN number, though I suspected that was the key. The ARFCN I was able to interpret from the chart on this page that I found from searching: http://gsmfordummies.com/intro/intro.shtml My numbers are in the 850 mhz range, but that's only when the network mode is set to 2g.

On 3g, the AFRCN changes to 0, and the UARFCN value becomes the one to watch. My number is either 512 or 4385. Reading from your post, apparently I'm switching between the two frequencies.

Interestingly the RSSI values, which I'm interpreting as signal strength are lower for 3G (around -100), than for 2G (in the -85 range), but voice quality and call stability are better in 3g even with the lower signal strength.

I'm thinking of building this coffee can antenna as an experiment, which works at 1900 mhz.

<a href="http://www.youtube.com/v/zwNZGuKzGWY&rel=1" target="_blank">http://www.youtube.com/v/zwNZGuKzGWY&rel=1</a>

I have no idea how to change the dimensions in order to build an 850 mhz one. The video is good, but unfortunately there's no technical information presented. But since I can get 1900 some of the time, I can see if the can antenna boosts the signal a bit.

Thanks for the camera button turn off. Previously I couldn't find a way to close the the engineering mode window other than turning off the phone.

[MikeDez]

Hey no problem, i'm glad I could help. Please post the results of your little experiment, i'd like to hear what you get.