RC7620-1 sends an ERROR response if using 4G SIM

IoT Modules RC76
1

I have two devices, which both contain RC7620-1 modules.
I have two SIMS: 2G SIM and 4G SIM

The device #1 can create a network connection with both SIMS.
The device #2 can create a network connection with 2G SIM, but with 4G SIM the connection fails.

I send the following AT commands at startup:
AT+CMEE=1
AT!MUXMODE=2
AT+CMUX=0,0,5,512
And then I send the further AT commands in DLCI1.

The device #1 and a successful connection with 4G SIM:

[14:32:12:532] 12:32:11+0005 24: dlci_recv_data():Sending 6 bytes to DLCI 1:␊
[14:32:12:532] 41 54 49 33 0D 0A                               | ATI3..␊
[14:32:12:666] 12:32:11+0039 24: dlci_send_data():Received 208 from DLCI 1:␊
[14:32:12:666] 0D 0A 4D 61 6E 75 66 61 63 74 75 72 65 72 3A 20 | ..Manufacturer: ␊
[14:32:12:666] 53 69 65 72 72 61 20 57 69 72 65 6C 65 73 73 2C | Sierra Wireless,␊
[14:32:12:666] 20 49 6E 63 6F 72 70 6F 72 61 74 65 64 0D 0A 4D |  Incorporated..M␊
[14:32:12:666] 6F 64 65 6C 3A 20 52 43 37 36 32 30 2D 31 0D 0A | odel: RC7620-1..␊
[14:32:12:708] 52 65 76 69 73 69 6F 6E 3A 20 53 57 49 39 58 30 | Revision: SWI9X0␊
[14:32:12:708] 37 48 5F 30 30 2E 30 38 2E 30 37 2E 30 30 20 30 | 7H_00.08.07.00 0␊
[14:32:12:708] 63 65 34 63 31 20 6A 65 6E 6B 69 6E 73 20 32 30 | ce4c1 jenkins 20␊
[14:32:12:708] 32 31 2F 30 33 2F 31 37 20 30 32 3A 31 38 3A 32 | 21/03/17 02:18:2␊
[14:32:12:708] 30 0D 0A 49 4D 45 49 3A 20 -- -- -- -- -- -- -- | 0..IMEI: --------␊
[14:32:12:708] -- -- -- -- -- -- -- -- 0D 0A 49 4D 45 49 20 53 | ---------..IMEI S␊
[14:32:12:708] 56 3A 20 31 37 0D 0A 46 53 4E 3A 20 37 54 32 31 | V: 17..FSN: 7T21␊
[14:32:12:708] 39 34 30 32 31 33 31 33 42 31 0D 0A 2B 47 43 41 | 94021313B1..+GCA␊
[14:32:12:749] 50 3A 20 2B 43 47 53 4D 0D 0A 0D 0A 4F 4B 0D 0A | P: +CGSM....OK..␊
[14:32:12:749] 12:32:11+0090 24: dlci_recv_data():Sending 11 bytes to DLCI 1:␊
[14:32:12:749] 41 54 2B 43 54 5A 52 3D 31 0D 0A                | AT+CTZR=1..␊
[14:32:12:875] 12:32:11+0010 24: dlci_send_data():Received 6 from DLCI 1:␊
[14:32:12:875] 0D 0A 4F 4B 0D 0A                               | ..OK..␊
[14:32:12:875] 12:32:11+0010 24: dlci_recv_data():Sending 11 bytes to DLCI 1:␊
[14:32:12:875] 41 54 2B 43 54 5A 55 3D 31 0D 0A                | AT+CTZU=1..␊
[14:32:12:966] 12:32:11+0010 24: dlci_send_data():Received 6 from DLCI 1:␊
[14:32:12:966] 0D 0A 4F 4B 0D 0A                               | ..OK..␊
...

The device #2 and a failed connection with 4G SIM:

[13:27:44:340] 11:27:41+0033 24: dlci_recv_data():Sending 6 bytes to DLCI 1:␊
[13:27:44:340] 41 54 49 33 0D 0A                               | ATI3..␊
[13:27:44:488] 11:27:41+0039 24: dlci_send_data():Received 208 from DLCI 1:␊
[13:27:44:488] 0D 0A 4D 61 6E 75 66 61 63 74 75 72 65 72 3A 20 | ..Manufacturer: ␊
[13:27:44:488] 53 69 65 72 72 61 20 57 69 72 65 6C 65 73 73 2C | Sierra Wireless,␊
[13:27:44:488] 20 49 6E 63 6F 72 70 6F 72 61 74 65 64 0D 0A 4D |  Incorporated..M␊
[13:27:44:488] 6F 64 65 6C 3A 20 52 43 37 36 32 30 2D 31 0D 0A | odel: RC7620-1..␊
[13:27:44:532] 52 65 76 69 73 69 6F 6E 3A 20 53 57 49 39 58 30 | Revision: SWI9X0␊
[13:27:44:532] 37 48 5F 30 30 2E 30 38 2E 32 34 2E 30 32 20 66 | 7H_00.08.24.02 f␊
[13:27:44:532] 39 30 63 62 64 20 6A 65 6E 6B 69 6E 73 20 32 30 | 90cbd jenkins 20␊
[13:27:44:532] 32 32 2F 30 33 2F 32 31 20 30 33 3A 34 37 3A 35 | 22/03/21 03:47:5␊
[13:27:44:532] 34 0D 0A 49 4D 45 49 3A 20 -- -- -- -- -- -- -- | 4..IMEI: --------␊
[13:27:44:532] -- -- -- -- -- -- -- -- 0D 0A 49 4D 45 49 20 53 | ---------..IMEI S␊
[13:27:44:532] 56 3A 20 31 39 0D 0A 46 53 4E 3A 20 43 4E 33 30 | V: 19..FSN: CN30␊
[13:27:44:532] 39 36 32 30 32 31 31 34 42 31 0D 0A 2B 47 43 41 | 96202114B1..+GCA␊
[13:27:44:569] 50 3A 20 2B 43 47 53 4D 0D 0A 0D 0A 4F 4B 0D 0A | P: +CGSM....OK..␊
[13:27:44:569] 11:27:41+0088 24: dlci_recv_data():Sending 11 bytes to DLCI 1:␊
[13:27:44:569] 41 54 2B 43 54 5A 52 3D 31 0D 0A                | AT+CTZR=1..␊
[13:27:44:632] 11:27:41+0011 24: dlci_send_data():Received 9 from DLCI 1:␊
[13:27:44:632] 0D 0A 45 52 52 4F 52 0D 0A                      | ..ERROR..␊
[13:27:44:679] 11:27:41+0010 24: dlci_recv_data():Sending 11 bytes to DLCI 1:␊
[13:27:44:679] 41 54 2B 43 54 5A 55 3D 31 0D 0A                | AT+CTZU=1..␊
[13:27:44:756] 11:27:41+0011 24: dlci_send_data():Received 9 from DLCI 1:␊
[13:27:44:756] 0D 0A 45 52 52 4F 52 0D 0A                      | ..ERROR..␊
...

Does anybody have any idea why the RC module in device #2 sends an ERROR response to “AT+CTZR=1” and “AT+CTZU=1” commands?

2

They are using different firmware version

Are they having same APN setting?

Did you also compare at!gstatus?

3

The responses to AT+CGDCONT? are the same in both devices, so APN settings are the same.

The device #1 and a successful connection with 4G SIM, AT!GSTATUS? :

[16:32:45:144] 14:21:07+0091 24: dlci_recv_data():Sending 13 bytes to DLCI 1:␊
[16:32:45:165] 41 54 21 47 53 54 41 54 55 53 3F 0D 0A          | AT!GSTATUS?..␊
[16:32:45:672] 14:21:08+0010 24: dlci_send_data():Received 512 from DLCI 1:␊
[16:32:45:672] 0D 0A 21 47 53 54 41 54 55 53 3A 20 0D 0A 43 75 | ..!GSTATUS: ..Cu␊
[16:32:45:715] 72 72 65 6E 74 20 54 69 6D 65 3A 20 20 31 35 09 | rrent Time:  15.␊
[16:32:45:715] 09 54 65 6D 70 65 72 61 74 75 72 65 3A 20 33 35 | .Temperature: 35␊
[16:32:45:715] 0D 0A 4D 6F 64 65 6D 20 4D 69 74 69 67 61 74 65 | ..Modem Mitigate␊
[16:32:45:715] 20 4C 65 76 65 6C 3A 20 30 09 09 4D 6F 64 65 6D |  Level: 0..Modem␊
[16:32:45:715] 50 72 6F 63 20 4D 69 74 69 67 61 74 65 20 4C 65 | Proc Mitigate Le␊
[16:32:45:715] 76 65 6C 3A 20 30 09 0D 0A 52 65 73 65 74 20 43 | vel: 0...Reset C␊
[16:32:45:715] 6F 75 6E 74 65 72 3A 20 36 09 09 4D 6F 64 65 3A | ounter: 6..Mode:␊
[16:32:45:758] 20 20 20 20 20 20 20 20 4F 4E 4C 49 4E 45 20 20 |         ONLINE  ␊
[16:32:45:758] 20 20 20 20 20 20 20 0D 0A 53 79 73 74 65 6D 20 |        ..System ␊
[16:32:45:758] 6D 6F 64 65 3A 20 20 20 4C 54 45 20 20 20 20 20 | mode:   LTE     ␊
[16:32:45:758] 20 20 20 09 50 53 20 73 74 61 74 65 3A 20 20 20 |    .PS state:   ␊
[16:32:45:758] 20 41 74 74 61 63 68 65 64 20 20 20 20 20 0D 0A |  Attached     ..␊
[16:32:45:758] 49 4D 53 20 72 65 67 20 73 74 61 74 65 3A 20 4E | IMS reg state: N␊
[16:32:45:758] 4F 54 20 52 45 47 49 53 54 45 52 45 44 20 20 09 | OT REGISTERED  .␊
[16:32:45:758] 49 4D 53 20 6D 6F 64 65 3A 20 20 20 20 4E 6F 72 | IMS mode:    Nor␊
[16:32:45:800] 6D 61 6C 20 20 20 20 20 20 20 0D 0A 49 4D 53 20 | mal       ..IMS ␊
[16:32:45:800] 53 72 76 20 53 74 61 74 65 3A 20 4E 4F 20 53 4D | Srv State: NO SM␊
[16:32:45:800] 53 2C 4E 4F 20 56 6F 49 50 20 20 20 20 20 20 20 | S,NO VoIP       ␊
[16:32:45:800] 20 20 20 0D 0A 4C 54 45 20 62 61 6E 64 3A 20 20 |    ..LTE band:  ␊
[16:32:45:800] 20 20 20 20 42 33 20 20 20 20 20 09 09 4C 54 45 |     B3     ..LTE␊
[16:32:45:800] 20 62 77 3A 20 20 20 20 20 20 32 30 20 4D 48 7A |  bw:      20 MHz␊
[16:32:45:800] 20 20 0D 0A 4C 54 45 20 52 78 20 63 68 61 6E 3A |   ..LTE Rx chan:␊
[16:32:45:843] 20 20 20 31 35 39 38 09 09 4C 54 45 20 54 78 20 |    1598..LTE Tx ␊
[16:32:45:843] 63 68 61 6E 3A 20 31 39 35 39 38 0D 0A 4C 54 45 | chan: 19598..LTE␊
[16:32:45:843] 20 43 41 20 73 74 61 74 65 3A 20 20 49 4E 41 43 |  CA state:  INAC␊
[16:32:45:843] 54 49 56 45 20 20 20 20 0D 0A 45 4D 4D 20 73 74 | TIVE    ..EMM st␊
[16:32:45:843] 61 74 65 3A 20 20 20 20 20 52 65 67 69 73 74 65 | ate:     Registe␊
[16:32:45:843] 72 65 64 20 20 20 20 20 09 4E 6F 72 6D 61 6C 20 | red     .Normal ␊
[16:32:45:843] 53 65 72 76 69 63 65 20 0D 0A 52 52 43 20 73 74 | Service ..RRC st␊
[16:32:45:886] 61 74 65 3A 20 20 20 20 20 52 52 43 20 43 6F 6E | ate:     RRC Con␊
[16:32:45:886] 6E 65 63 74 65 64 20 20 0D 0A 0D 0A 50 43 43 20 | nected  ....PCC ␊
[16:32:45:972] 14:21:08+0010 24: dlci_send_data():Received 196 from DLCI 1:␊
[16:32:45:972] 52 78 4D 20 52 53 53 49 3A 20 20 2D 35 39 09 09 | RxM RSSI:  -59..␊
[16:32:46:014] 52 53 52 50 20 28 64 42 6D 29 3A 20 20 2D 39 31 | RSRP (dBm):  -91␊
[16:32:46:014] 0D 0A 50 43 43 20 52 78 44 20 52 53 53 49 3A 20 | ..PCC RxD RSSI: ␊
[16:32:46:014] 20 2D 39 33 09 09 52 53 52 50 20 28 64 42 6D 29 |  -93..RSRP (dBm)␊
[16:32:46:014] 3A 20 20 2D 31 34 30 0D 0A 54 78 20 50 6F 77 65 | :  -140..Tx Powe␊
[16:32:46:014] 72 3A 20 20 20 20 20 20 2D 2D 09 09 54 41 43 3A | r:      --..TAC:␊
[16:32:46:014] 20 20 20 20 20 20 20 20 20 30 31 36 30 20 28 33 |          0160 (3␊
[16:32:46:014] 35 32 29 0D 0A 52 53 52 51 20 28 64 42 29 3A 20 | 52)..RSRQ (dB): ␊
[16:32:46:062] 20 20 20 20 2D 39 09 09 43 65 6C 6C 20 49 44 3A |     -9..Cell ID:␊
[16:32:46:062] 20 20 20 20 20 30 30 32 32 46 37 30 33 20 28 32 |      0022F703 (2␊
[16:32:46:062] 32 39 31 34 35 39 29 0D 0A 53 49 4E 52 20 28 64 | 291459)..SINR (d␊
[16:32:46:062] 42 29 3A 20 20 20 20 20 20 34 2E 34 0D 0A 0D 0A | B):      4.4....␊
[16:32:46:062] 4F 4B 0D 0A                                     | OK..␊

The device #2 and a failed connection with 4G SIM, AT!GSTATUS?:

[16:43:16:044] 14:43:09+0088 24: dlci_recv_data():Sending 13 bytes to DLCI 1:␊
[16:43:16:044] 41 54 21 47 53 54 41 54 55 53 3F 0D 0A          | AT!GSTATUS?..␊
[16:43:16:323] 14:43:09+0041 24: dlci_send_data():Received 512 from DLCI 1:␊
[16:43:16:323] 0D 0A 21 47 53 54 41 54 55 53 3A 20 0D 0A 43 75 | ..!GSTATUS: ..Cu␊
[16:43:16:323] 72 72 65 6E 74 20 54 69 6D 65 3A 20 20 31 34 09 | rrent Time:  14.␊
[16:43:16:366] 09 54 65 6D 70 65 72 61 74 75 72 65 3A 20 32 39 | .Temperature: 29␊
[16:43:16:366] 0D 0A 4D 6F 64 65 6D 20 4D 69 74 69 67 61 74 65 | ..Modem Mitigate␊
[16:43:16:366] 20 4C 65 76 65 6C 3A 20 30 09 09 4D 6F 64 65 6D |  Level: 0..Modem␊
[16:43:16:366] 50 72 6F 63 20 4D 69 74 69 67 61 74 65 20 4C 65 | Proc Mitigate Le␊
[16:43:16:366] 76 65 6C 3A 20 30 09 0D 0A 52 65 73 65 74 20 43 | vel: 0...Reset C␊
[16:43:16:366] 6F 75 6E 74 65 72 3A 20 31 09 09 4D 6F 64 65 3A | ounter: 1..Mode:␊
[16:43:16:366] 20 20 20 20 20 20 20 20 4F 4E 4C 49 4E 45 20 20 |         ONLINE  ␊
[16:43:16:366] 20 20 20 20 20 20 20 0D 0A 53 79 73 74 65 6D 20 |        ..System ␊
[16:43:16:409] 6D 6F 64 65 3A 20 20 20 47 53 4D 20 20 20 20 20 | mode:   GSM     ␊
[16:43:16:409] 20 20 20 09 50 53 20 73 74 61 74 65 3A 20 20 20 |    .PS state:   ␊
[16:43:16:409] 20 4E 6F 74 20 61 74 74 61 63 68 65 64 20 0D 0A |  Not attached ..␊
[16:43:16:409] 49 4D 53 20 72 65 67 20 73 74 61 74 65 3A 20 4E | IMS reg state: N␊
[16:43:16:409] 4F 54 20 52 45 47 49 53 54 45 52 45 44 20 20 09 | OT REGISTERED  .␊
[16:43:16:409] 49 4D 53 20 6D 6F 64 65 3A 20 20 20 20 4E 6F 72 | IMS mode:    Nor␊
[16:43:16:409] 6D 61 6C 20 20 20 20 20 20 20 0D 0A 49 4D 53 20 | mal       ..IMS ␊
[16:43:16:452] 53 72 76 20 53 74 61 74 65 3A 20 4E 4F 20 53 4D | Srv State: NO SM␊
[16:43:16:452] 53 2C 4E 4F 20 56 6F 49 50 20 20 20 20 20 20 20 | S,NO VoIP       ␊
[16:43:16:452] 20 20 20 0D 0A 47 53 4D 20 62 61 6E 64 3A 20 20 |    ..GSM band:  ␊
[16:43:16:452] 20 20 20 20 47 53 4D 39 30 30 20 20 20 20 20 0D |     GSM900     .␊
[16:43:16:452] 0A 47 53 4D 20 63 68 61 6E 6E 65 6C 3A 20 20 20 | .GSM channel:   ␊
[16:43:16:452] 38 0D 0A 47 4D 4D 20 28 50 53 29 20 73 74 61 74 | 8..GMM (PS) stat␊
[16:43:16:452] 65 3A 44 45 52 45 47 49 53 54 45 52 45 44 20 20 | e:DEREGISTERED  ␊
[16:43:16:452] 20 09 50 4C 4D 4E 20 53 45 41 52 43 48 20 20 20 |  .PLMN SEARCH   ␊
[16:43:16:495] 20 0D 0A 4D 4D 20 28 43 53 29 20 73 74 61 74 65 |  ..MM (CS) state␊
[16:43:16:495] 3A 20 49 44 4C 45 20 20 20 20 20 20 20 20 20 20 | : IDLE          ␊
[16:43:16:495] 20 09 50 4C 4D 4E 20 53 45 41 52 43 48 20 20 20 |  .PLMN SEARCH   ␊
[16:43:16:495] 20 0D 0A 0D 0A 53 65 72 76 69 6E 67 20 63 65 6C |  ....Serving cel␊
[16:43:16:495] 6C 3A 20 20 30 20 28 55 6E 6B 6E 6F 77 6E 20 20 | l:  0 (Unknown  ␊
[16:43:16:495] 20 20 29 0D 0A 52 58 20 6C 65 76 65 6C 20 28 64 |   )..RX level (d␊
[16:43:16:495] 42 6D 29 3A 30 2E 30 85 D8 44 0F 82 20 09 4C 41 | Bm):0.0..D.. .LA␊
[16:43:16:576] 14:43:10+0029 24: dlci_send_data():Received 86 from DLCI 1:␊
[16:43:16:576] 43 3A 20 20 20 20 20 20 20 20 20 30 30 30 30 20 | C:         0000 ␊
[16:43:16:576] 28 30 29 0D 0A 47 50 52 53 20 73 74 61 74 65 3A | (0)..GPRS state:␊
[16:43:16:576] 20 20 20 20 47 50 52 53 20 49 44 4C 45 20 20 20 |     GPRS IDLE   ␊
[16:43:16:576] 20 20 20 09 43 65 6C 6C 20 49 44 3A 20 20 20 20 |    .Cell ID:    ␊
[16:43:16:576] 20 46 46 46 46 46 46 46 46 20 28 2D 31 29 0D 0A |  FFFFFFFF (-1)..␊
[16:43:16:576] 0D 0A 4F 4B 0D 0A                               | ..OK..␊
4

So the “AT!GSTATUS?” responses reveal that
The device #1 and a successful connection with 4G SIM => System mode: LTE
The device #2 and a failed connection with 4G SIM => System mode: GSM
But why the system mode is different?

5

have you tried with same FW as the OK device?
is it the same for AT!IMPREF? for the carrier setting?
How about forcing the technology to be LTE mode with AT!SELRAT command?
Have you compared if AT!BAND is set to automatic?

6

#>>have you tried with same FW as the OK device?
No, but I have a device #3, which has the same FW as failing device #2, and with this device #3 the 4G connection succeeds with the same 4G SIM.

#>>How about forcing the technology to be LTE mode with AT!SELRAT command?
I tried “AT!SELRAT=06” to the failing device #2, but it did not help.

#>>is it the same for AT!IMPREF? for the carrier setting?
#>>Have you compared if AT!BAND is set to automatic?
The device #1 and a successful connection with 4G SIM, “AT!IMPREF?” and “AT!BAND?”:

[12:55:14:384] 10:55:11+2786 24: dlci_recv_data():Sending 12 bytes to DLCI 1:␊
[12:55:14:384] 41 54 21 49 4D 50 52 45 46 3F 0D 0A             | AT!IMPREF?..␊
[12:55:14:622] 10:55:11+0033 24: dlci_send_data():Received 323 from DLCI 1:␊
[12:55:14:622] 0D 0A 21 49 4D 50 52 45 46 3A 20 0D 0A 20 70 72 | ..!IMPREF: .. pr␊
[12:55:14:622] 65 66 65 72 72 65 64 20 66 77 20 76 65 72 73 69 | eferred fw versi␊
[12:55:14:622] 6F 6E 3A 20 20 20 20 30 30 2E 30 38 2E 30 37 2E | on:    00.08.07.␊
[12:55:14:622] 30 30 0D 0A 20 70 72 65 66 65 72 72 65 64 20 63 | 00.. preferred c␊
[12:55:14:665] 61 72 72 69 65 72 20 6E 61 6D 65 3A 20 20 47 45 | arrier name:  GE␊
[12:55:14:665] 4E 45 52 49 43 0D 0A 20 70 72 65 66 65 72 72 65 | NERIC.. preferre␊
[12:55:14:665] 64 20 63 6F 6E 66 69 67 20 6E 61 6D 65 3A 20 20 | d config name:  ␊
[12:55:14:665] 20 47 45 4E 45 52 49 43 5F 30 30 31 2E 30 38 31 |  GENERIC_001.081␊
[12:55:14:665] 5F 30 30 30 0D 0A 20 70 72 65 66 65 72 72 65 64 | _000.. preferred␊
[12:55:14:665] 20 73 75 62 70 72 69 20 69 6E 64 65 78 3A 20 20 |  subpri index:  ␊
[12:55:14:665] 30 30 30 0D 0A 20 63 75 72 72 65 6E 74 20 66 77 | 000.. current fw␊
[12:55:14:708] 20 76 65 72 73 69 6F 6E 3A 20 20 20 20 20 20 30 |  version:      0␊
[12:55:14:708] 30 2E 30 38 2E 30 37 2E 30 30 0D 0A 20 63 75 72 | 0.08.07.00.. cur␊
[12:55:14:708] 72 65 6E 74 20 63 61 72 72 69 65 72 20 6E 61 6D | rent carrier nam␊
[12:55:14:708] 65 3A 20 20 20 20 47 45 4E 45 52 49 43 0D 0A 20 | e:    GENERIC.. ␊
[12:55:14:708] 63 75 72 72 65 6E 74 20 63 6F 6E 66 69 67 20 6E | current config n␊
[12:55:14:708] 61 6D 65 3A 20 20 20 20 20 47 45 4E 45 52 49 43 | ame:     GENERIC␊
[12:55:14:708] 5F 30 30 31 2E 30 38 31 5F 30 30 30 0D 0A 20 63 | _001.081_000.. c␊
[12:55:14:751] 75 72 72 65 6E 74 20 73 75 62 70 72 69 20 69 6E | urrent subpri in␊
[12:55:14:751] 64 65 78 3A 20 20 20 20 30 30 30 0D 0A 0D 0A 4F | dex:    000....O␊
[12:55:14:751] 4B 0D 0A                                        | K..␊

[12:57:45:957] 10:57:43+0090 24: dlci_recv_data():Sending 10 bytes to DLCI 1:␊
[12:57:45:957] 41 54 21 42 41 4E 44 3F 0D 0A                   | AT!BAND?..␊
[12:57:45:957] cmdModemCommand():Sent 10 bytes OK to ch 1␊
[12:57:46:069] 10:57:43+0022 24: dlci_send_data():Received 36 from DLCI 1:␊
[12:57:46:069] 0D 0A 49 6E 64 65 78 2C 20 4E 61 6D 65 0D 0A 30 | ..Index, Name..0␊
[12:57:46:095] 30 2C 20 41 6C 6C 20 62 61 6E 64 73 0D 0A 0D 0A | 0, All bands....␊
[12:57:46:095] 4F 4B 0D 0A                                     | OK..␊

The device #2 and a failed connection with 4G SIM, “AT!IMPREF?” and “AT!BAND?”:

[12:46:29:585] 10:46:22+0588 24: dlci_recv_data():Sending 12 bytes to DLCI 1:␊
[12:46:29:606] 41 54 21 49 4D 50 52 45 46 3F 0D 0A             | AT!IMPREF?..␊
[12:46:29:788] 10:46:22+0081 24: dlci_send_data():Received 323 from DLCI 1:␊
[12:46:29:788] 0D 0A 21 49 4D 50 52 45 46 3A 20 0D 0A 20 70 72 | ..!IMPREF: .. pr␊
[12:46:29:788] 65 66 65 72 72 65 64 20 66 77 20 76 65 72 73 69 | eferred fw versi␊
[12:46:29:788] 6F 6E 3A 20 20 20 20 30 30 2E 30 38 2E 32 34 2E | on:    00.08.24.␊
[12:46:29:788] 30 32 0D 0A 20 70 72 65 66 65 72 72 65 64 20 63 | 02.. preferred c␊
[12:46:29:788] 61 72 72 69 65 72 20 6E 61 6D 65 3A 20 20 47 45 | arrier name:  GE␊
[12:46:29:832] 4E 45 52 49 43 0D 0A 20 70 72 65 66 65 72 72 65 | NERIC.. preferre␊
[12:46:29:832] 64 20 63 6F 6E 66 69 67 20 6E 61 6D 65 3A 20 20 | d config name:  ␊
[12:46:29:832] 20 47 45 4E 45 52 49 43 5F 30 30 31 2E 31 31 30 |  GENERIC_001.110␊
[12:46:29:832] 5F 30 30 30 0D 0A 20 70 72 65 66 65 72 72 65 64 | _000.. preferred␊
[12:46:29:832] 20 73 75 62 70 72 69 20 69 6E 64 65 78 3A 20 20 |  subpri index:  ␊
[12:46:29:832] 30 30 30 0D 0A 20 63 75 72 72 65 6E 74 20 66 77 | 000.. current fw␊
[12:46:29:832] 20 76 65 72 73 69 6F 6E 3A 20 20 20 20 20 20 30 |  version:      0␊
[12:46:29:875] 30 2E 30 38 2E 32 34 2E 30 32 0D 0A 20 63 75 72 | 0.08.24.02.. cur␊
[12:46:29:875] 72 65 6E 74 20 63 61 72 72 69 65 72 20 6E 61 6D | rent carrier nam␊
[12:46:29:875] 65 3A 20 20 20 20 47 45 4E 45 52 49 43 0D 0A 20 | e:    GENERIC.. ␊
[12:46:29:875] 63 75 72 72 65 6E 74 20 63 6F 6E 66 69 67 20 6E | current config n␊
[12:46:29:875] 61 6D 65 3A 20 20 20 20 20 47 45 4E 45 52 49 43 | ame:     GENERIC␊
[12:46:29:875] 5F 30 30 31 2E 31 31 30 5F 30 30 30 0D 0A 20 63 | _001.110_000.. c␊
[12:46:29:875] 75 72 72 65 6E 74 20 73 75 62 70 72 69 20 69 6E | urrent subpri in␊
[12:46:29:913] 64 65 78 3A 20 20 20 20 30 30 30 0D 0A 0D 0A 4F | dex:    000....O␊
[12:46:29:913] 4B 0D 0A                                        | K..␊

[12:48:31:131] 10:48:24+2418 24: dlci_recv_data():Sending 10 bytes to DLCI 1:␊
[12:48:31:131] 41 54 21 42 41 4E 44 3F 0D 0A                   | AT!BAND?..␊
[12:48:31:185] 10:48:24+0022 24: dlci_send_data():Received 36 from DLCI 1:␊
[12:48:31:185] 0D 0A 49 6E 64 65 78 2C 20 4E 61 6D 65 0D 0A 30 | ..Index, Name..0␊
[12:48:31:211] 30 2C 20 41 6C 6C 20 62 61 6E 64 73 0D 0A 0D 0A | 0, All bands....␊
[12:48:31:211] 4F 4B 0D 0A                                     | OK..␊
7

Then you need to capture qxdm log and contact distributor for investigation

8

OK. I have never captured qxdm logs.
I assume these are valid instructions for RC7620-1:

https://source.sierrawireless.com/resources/airprime/software/mbpl/mbpl-software-latest/#sthash.ZXRwiiKx.6tzg5lpm.dpbs

I am controlling RC7620-1 with an embedded MCU via USB interface, and it is not easy to replace the MCU with a Linux workstation.
Let’s see if I have time to study this deeper …

9

You might contact distributor first to see if there is easier method

10

OK, thanks for your help!