Q2678RD /w v7.43 generic cannot do 1st GSM registration


#1

Hi all, Forum Experts,

Describing my issues below, wondering if any one has experienced this? or have any views/opinoins/thoughts/etc?

We are using Q2687rd (aka Refreshed) module (with generic R7.43 firmware) within our ME. At certain locations in USA, this GPRS module cannot do a 1st time GSM registration. While a Siemens (currently Cinterion) MC56 at the same location, and with the same “fresh” SIM card, has no problems in registering in about 15secs.

Signal strength is good - more then 20 rssi on average (one example: +CSQ:.21,99) for both Q2687R and MC56. SIM card is AT&T.

My layperson’s guess is that Q2687R is trying to find a PLMN that is not there and can not pull off it. While for some reasons, MC56 has no such issues.

I will try to provide more info/data if its possible. There’s no way to get a more detail log from my side. :-/

Thanks in advance.
Ed


#2

What does AT+COPS=? tell you in this situation?

Or AT+CCED=0,16

Is it camping-on to the “wrong” network in “Emergency Calls Only” (+WIND: 7) mode?

What kind of SIM is it? Is it a special multi-operator “roaming” SIM?


#3

Thanks for chiming in.
Hard to say, Neil. As this “remote” site’s operator is not technical enough to do deeper debugging. So far, from the limited logs I can gather, I have more/less arrive at the following conclusions (barring more datapoints that I can scrap up):

  1. Signal strength from the tower connected to is between 4 and 5 bars (very strong)
  2. First time GSM registration with Siemens (MC56) is about 6 sec ( very good)
  3. Second time registration with Wavecom in about 6 sec (very good)
  4. First time GSM registration and Second time registrations have ROAMED (all firmwares Wavecom and Siemens)
  5. None of the Wavecom first time registrations on any firmware recorded any error codes
  6. All of the Wavecom first time registrations on any firmware recorded CCREG of 0,2 (searching for network)
  7. All of the Wavecom firmware will allow complete a roam connection when/once the tower is identified on the SIM card (recorded after the first connection)

I am open to the “camping” theory, but wondering if others here hear more of such behaviors? What would cause such a “camping” trip? Wild guess, PLMN algo failure? or…?

Not sure what kind of SIM is being use at that side - only that its AT&T card. Just curious questions, what kind(s) of SIM are there? Some sort of “tiered service plans” perhaps?

Anyone else having the same/similar experiences please?


#4

How do you determine that?

The Q26 istelf does not report signal strength in “bars”…

I had a problem with one client using an international roaming SIM - in certain cases, it would fail to register even though AT+COPS=? showed that it could “see” permitted networks.

However, this was after losing coverage - I don’t know about “first registration”.

Apparently, this SIM had some sort of “least-cost algorithm” to determine which network to choose - so that might have had something to do with it.

Does issuing AT+COPS=0 help?
See: https://forum.sierrawireless.com/t/undocumented-side-effect-of-at-cops-0/4871/2


#5

Quick reply, Neil, you are correct about the bar; that was the device (UI display) reading. From log, I can see reply such as +CSQ:.28,99 etc. etc. The Siemens can get a successful registration at +CSQ:.17,99, so my current thoughts are that signal strength/quality at that location is not the issue.

Say, anyone from SierraWireless Canada/NorthAmerica in the house (forum) can comment?
:wink: Or are you representing SiWi, Neil?

Re your forum discussion on PLMN selection, interesting that why would this matter (unsolved?) for Wavecom yet? Even at R7.43? :unamused: Or is this already another known issue…I will have to go back to the firmware release notes again.


#6

No - SiWi do not actively monitor the forum.

If you want to contact SiWi, then you have to go direct to your FAE or Distributor

No.


#7

Getting “stonewall” (vague) replies from local FAEs.

Or are you representing SiWi
No.
Got it. Appreciate your shading some lights. :slight_smile:

Even with “least cost” algo, should be a bug if other modules work and Wavecom’s doesn’t. Or did I get this wrong (“industry norm”)?


#8

Yes, I suspect it is a bug.


#9

I believe you may be facing a known issue related to non-unique TLLI (see 3GPP TS 24.008 for more info on what it means) being used by the module. It is fixed in the latest firmware beta (R7.45.1). Try to get it from your FAE or distributor.


#10

Haven’t checked 3GPP TS 24.008 yet, but Wikipedia says the TLLI is to do with GPRS:

en.wikipedia.org/wiki/TLLI

I thought the OP’s problem was GSM registration?


#11

Does the R745.0 can be used in AT&T network?


#12

Hi SPI,

Don’t mind me asking, how do you know to suspect TLLI?

Looking at the 7.45 ReleaseNotes (here: sierrawireless.com/Support/A … _7_45.aspx ),I don’t seems to notice any mention of TLLI?

Please explain your postulations and assumptions if you don’t mind.

Hi Neil,
Not sure, but my limited understanding is that GSM registration needs to happen 1st before GPRS “session” can be establish. If GSM registration is failing (as it is), it never got to the GPRS session setup.

Thanks to both in advance.


#13

Since no one seems to knows, one more question won’t hurt… what’s with the AT&T certification for Q2687rd (aka Refresh) firmware?

For example, I refer to the 7.44 firmware release notes here:
sierrawireless.com/Support/A … _7_44.aspx

From quick calc, seems that one of the noticeable difference between is the binary size delta of 16bytes for 7.44 and 7.44.1; while there’s a binary size diff of 532 bytes between 7.44.1 (ATT certified) and Vodafone certified 7.44.3. :unamused:

Speculating that 16bytes looks like a basic checksum? and (Vodafone) a 4096bit public key cert for 7.44.3?

Any other thoughts/hypothesis/speculations? Cheers.


#14

Indeed

Yes - that’s why I was querying SPI’s suggestion of some thing that appeared to be GPRS-related.


#15

Hi all,

While my suspicion of the “PLMN” issue was not fully proven, what I do know is that recently (Aug?) released 7.45.1 certified firmware works to solve the “1st GSM registration” issue that I was experiencing for almost the last 1yr.

Now if only Sierra can give a more comprehensive answer – if Siemens can do it (release highly compliant/working firmware), why not Sierra? :stuck_out_tongue:

Special thanks to awneil.

cheers. Ed.