Change APN using +cgdcont command

IoT Modules MC/EM Series
1

Hi I have an interesting problem…

I am using a EM7450 modem. I am using the +cgdcont command to change the APN for profile 1. Since I am using a AT&T card, the APN is m2m.com.attz. I noticed a few times when I changed the APN to something like mickeymouse, the connection remains active even though this is obviously the wrong APN for the SIM card.
Shouldn’t the connection go down when I change the APN to something bogus?

2

Hello,

at!custom -

“SINGLEAPNSWITCH” Indicate device behavior
when changing APN name, username, or password.
:
• 0 = Do nothing
• 1 = Device detaches and re-attaches after changing APN information
• 2 = Power-cycle the UE

thanks,
James

3

It is set to 1. Should I see the ttyUSB* devices disappear and reappear after a while?

4

It is set to 1 and when I changed the APN, I do not see the module disconnect from the USB bus. Did you mean it detaches and reattaches from the cell network?

What was so strange to me is that the +cgdcont command with the bogus APN was sent and acknowledged by the module, but the cell connection kept going as if nothing happened. I was expecting the network to be brought down by the bogus APN.

5

Yes , it won’t disconnect from the USB bus.
option 2 will reset the modem

6

So if the APN I entered is bogus, when it reattaches to the network again, the PDP connection should drop right?

7

yes. you need to reset the modem after programming !custom

8

Thanks again for your reply.

Actually I do not want to program !custom. I will just leave the default settings at 1.

What I like to make sure is that when I program the APN with either a valid or bogus setting using +cgdcont, the expected PDP connection behavior will result.

9

sorry I didn’t get the second part of your comment.

10

Thanks for your reply.

So if I use the +cgdcont command to program a bogus APN into a EM7455 module that has an active PDP connection, should it cause the PDP connection to be disrupted?

11

yes it will disconnect .
here is an example captured on my callbox:
default is the valid APN
bogus APN is not programmed in the callbox:

at+cgcontrdp
+CGCONTRDP: 1,5,default,192.168.2.2,8.8.8.8,

OK
at!custom?
!CUSTOM:
GPSENABLE 0x01
GPSLPM 0x01
IPV6ENABLE 0x01
UIM2ENABLE 0x01
SIMLPM 0x01
USBSERIALENABLE 0x01
SINGLEAPNSWITCH 0x01

OK
at+cgdcont?
+CGDCONT: 1,“IP”,“default”,“0.0.0.0”,0,0,0,0

OK

at!gstatus?
!GSTATUS:
Current Time: 37 Temperature: 28
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B4 LTE bw: 20 MHz
LTE Rx chan: 2150 LTE Tx chan: 20150
LTE CA state: NOT ASSIGNED
EMM state: Registered Normal Service
RRC state: RRC Idle
IMS reg state: No Srv

PCC RxM RSSI: -36 RSRP (dBm): -63
PCC RxD RSSI: -57 RSRP (dBm): -83
Tx Power: – TAC: 0001 (1)
RSRQ (dB): -6.0 Cell ID: 01A2D101 (27447553)
SINR (dB): 28.6

OK
at+cgcontrdp
+CGCONTRDP: 1,5,default,192.168.2.2,8.8.8.8,

OK
at+cgdcont=1,“ip”,“bogus”
OK
at+cgcontrdp
OK
at!gstatus?
!GSTATUS:
Current Time: 79 Temperature: 28
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Not attached
LTE band: B4 LTE bw: 20 MHz
LTE Rx chan: 2150 LTE Tx chan: 20150
LTE CA state: NOT ASSIGNED
EMM state: Deregistered Attaching
RRC state: RRC Idle
IMS reg state: No Srv

PCC RxM RSSI: -36 RSRP (dBm): -63
PCC RxD RSSI: -57 RSRP (dBm): -83
Tx Power: – TAC: 0001 (1)
RSRQ (dB): -6.0 Cell ID: 01A2D101 (27447553)
SINR (dB): 29.0

OK

at+cgcontrdp
OK
at+creg?
+CREG: 0,2

OK
a/
+CREG: 0,2

OK