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Way to confirm 3G FONA is actually on 3G not 2G network?
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Way to confirm 3G FONA is actually on 3G not 2G network?

by sgfulton on Tue Jun 12, 2018 10:55 am

Hi,

We've been successfully using the 2G FONA 808 cellular modem with a Ting 2G Sim card from Adafruit here in Georgia, USA. I had been intending to use the 808 in KY but recently (May 2018) discovered that 2G is no longer available from my research site in remote eastern KY. We have purchased the 3G FONA and are testing it with a T-Mobile 2G/3G/4G/LTE Sim card here in the office in Athens, GA. Can anyone tell me if there is a way to confirm that we are in fact on a 3G network and not 2G or 4G or something else? My advisor is doing the testing so I don't know all the specifics of the code and library provided by Adafruit, but I believe you instantiate it as "3G" so I assume it will only access a 3G network. However, I would like to know if there is some way to actually confirm that it's on a 3G network since we don't have 2G anymore in KY. We've never used these multiple network Sim cards before (e.g., 2G/3G/4G, etc.).

Thanks,
Stephanie

sgfulton
 
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Re: Way to confirm 3G FONA is actually on 3G not 2G network

by daveh225 on Tue Jun 12, 2018 11:52 pm

Try AT+CPSI? The response should indicate GSM (2G) or WCDMA (3G)

There are other 2G vs 3G relevant commands if you need more control.

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Re: Way to confirm 3G FONA is actually on 3G not 2G network

by sgfulton on Wed Jun 13, 2018 9:33 am

Thanks Dave, we'll check that out! If I need more info I'll be back with more questions!

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Re: Way to confirm 3G FONA is actually on 3G not 2G network

by sgfulton on Sun Jun 17, 2018 3:19 pm

Dave,

We tried the command you suggested below; here's the response we got (2nd line):

---> AT+CPSI?
<--- +CPSI: GSM,Online,310-260 0x1df8,8461,708 PCS 1900,-106,0,1-1

According to your statement in your previous comment, it appears we are on GSM or 2G. However, a Ting technician told me that T-Mobile 3G uses GSM also. Could you tell me what the other "relevant commands" are that would give us "more control" over which network we want to use?

Thanks,
Stephanie

sgfulton
 
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Re: Way to confirm 3G FONA is actually on 3G not 2G network

by daveh225 on Mon Jun 18, 2018 1:06 am

I got the GSM vs WCDMA = 2G vs 3G from a Google search, I'm no expert on this stuff so please understand I might be sending you in the wrong direction. :) The CPSI command I got from the SIMCOM manual that's linked from the Adafruit tutorial on the Fona 3G. Chapter 5 contains the commands dealing with the network. From your response it looks like PCS 1900 is a further qualifier to GSM. (Looking at the possible modes for the AT+CNBP preferred band selection and the example given in the manual - EGSM 900.) I believe the 1900 might be frequency. Can you get any information from the Ting technician as to how to differentiate between 2G and 3G on their network? It might be determined by frequency.

Other possible commands are AT+CNSMOD? The second digit should be:

1 - GSM
2 - GPRS
3 - EGPRS (EDGE)
4 - WCDMA
5 - HSDPA only
6 - HSUPA only
7 - HSPA (HSDPA and HSUPA)

I'm not sure if any of those would be definitive in determining 2G vs 3G.

AT+CCINFO? gives a whole host of information that is largely meaningless to me, but might help.

AT*CNTI? seems to give similar info as CNSMOD above. Note the * instead of the + in the command. That's how it's listed in the manual but from the intro it looks like you can use any character so I don't think it's important.

AT+CELLLOCK locks on to a specific 2G cell using an arfcn that can be obtained from CCINFO. I don't know what an arfcn is. :)

AT+CLUCELL locks on to a specific 3G cell using frequency and PSC obtained from CPSI.

If Ting can give you a bit more info maybe you can determine what you need from these various commands.

daveh225
 
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Re: Way to confirm 3G FONA is actually on 3G not 2G network

by daveh225 on Mon Jun 18, 2018 1:45 pm

Just noticed this on the tutorial page:

The American band version of the FONA 3G covers dual-band UMTS/HSDPA 850/1900MHz WCDMA + HSDPA.

In the USA, only AT&T has 850 MHz and 1900 MHz as the two supported HSPA bands. So if you use T-Mobile or a distributor of theirs, you will only get 2G support not full 3G! For 3G, stick to AT&T or check with the carrier that they have one of the dual-band UMTS/HSDPA 850/1900MHz WCDMA + HSDPA supported.


You may have to switch carriers. I'm using FreedomPop which uses the AT&T network and offers a free 4G LTE plan (up to 200MB) which is working for what I need, (falling back to 3G - don't know about 2G).

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