# MC7455 - Connection sequence to LTE network **URL:** \ **Category:** MC/EM Series\ **Created:** [November 4, 2022, 10:45am UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283 "2022-11-04T10:45:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 10:45am UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/1 "2022-11-04T10:45:31Z")
Hello there, To begin, i know there are severals topics dealing with what i’m going to ask but from the (maybe?) hundred of website i have visited and after reading many times the official AT documentation for my modem, i could not solve my problem so let me explain it and maybe this will help others in the future ! First, here are some **informations** about my modem and its **configuration** : ```auto AT!ENTERCND=“A710” OK ATI3 Manufacturer: Sierra Wireless, Incorporated Model: MC7455 Revision: SWI9X30C_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 0 AT+CPIN? +CPIN: READY OK AT+CGDCONT? +CGDCONT: 1,"IP","mobiledata","0.0.0.0",0,0,0,0 OK AT!GSTATUS? !GSTATUS: Current Time: 83664 Temperature: 41 Reset Counter: 7 Mode: ONLINE System mode: LTE AT+COPS? +COPS: 0,0,"Transatel Transatel",7 OK AT+COPS=? +COPS: (2,"Transatel","Transate","20801",7),(1,"Orange F","Orange","20801",2),(1,"F SFR","SFR"2 AT!IMPREF? !IMPREF: preferred fw version: 02.24.05.06 preferred carrier name: GENERIC preferred config name: GENERIC_002.02 AT!IMAGE? TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID FW 1 GOOD 130 0 0 ?_? 02.24.05.06_? FW 2 GOOD 1 0 0 ?_? 02.24.03.00_? FW 3 GOOD 129 0 0 ?_? 02.33.03.00_? FW 4 EMPTY 0 0 0 AT!CUSTOM? AT!CUSTOM: GPSENABLE 0x01 GPSLPM 0x01 UIM2ENABLE 0x01 SIMLPM 0x01 AT!PCINFO? State: Online LPM voters - Temp:0, Volt:0, User:0, W_DISABLE:0, IMSWITCH:0, BIOS:0, LWM2M:0, OMADM:0, FOTA:0 LPM persistenc AT!GETBAND? !GETBAND: B7 OK AT!RXDEN? !RXDEN: 01 OK AT!LTEINFO? !LTEINFO: Serving: EARFCN MCC MNC TAC CID Bd D U SNR PCI RSRQ RSRP RSSI RXLV 3000 208 01 52647 AT!USBCOMP? Config Index: 1 Config Type: 1 (Generic) Interface bitmask: 00001009 (diag,modem,mbim) OK ``` **Connection sequence** ```auto AT+CREG=1 OK AT+CGATT=1 OK AT+CGDCONT=1,"ip","mobiledata" OK AT+CGACT=1 OK ``` **Connection status** ```auto AT+CGATT? +CGATT: 1 OK AT+CGACT? +CGACT: 1,1 OK AT+CREG? +CREG: 1,1 OK AT+CGCONTRDP +CGCONTRDP: 1,5,mobiledata,10.141.37.59,,176.241.248.113,176.241.248.114 OK ``` So, as you can see, my modem seems to be connected to the operator network. Yet, the gateway is never given running +CGCONTRDP AT command which i don’t know why. (Also how am i supposed to get the subnet mask?) From there, i have my modem interface wwp0s20f0u2i12 which i configure with the IP adress, an arbitrary subnet mask of /30 and a gateway (also arbitrary). I also set the DNS, etc but when i try to ping from the modem interface, it does not work obviously. **Network setup** ```auto ip link set wwp0s20f0u2i12 down ip addr flush dev wwp0s20f0u2i12 ip link set wwp0s20f0u2i12 up ip addr add 10.141.37.59/30 dev wwp0s20f0u2i12 broadcast + ip link set mtu 1460 dev wwp0s20f0u2i12 ping -I wwp0s20f0u2i12 1.1.1.1 # not working ``` So i wanted to know what am i missing so i cannot have internet through my modem interface ? NB: I’m able to reach internet from the modem interface when i use mbim-network command and then configure my network as above but my goal is to use AT commands instead of mbim-network program ! ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 4, 2022, 11:09am UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/2 "2022-11-04T11:09:46Z")
Have you tried latest firmware? Have you tried at!scact=1,1 ? You can see here: > [@Example on establishing data connection by AT!SCACT via MBPL R20 driver](https://forum.sierrawireless.com/t/example-on-establishing-data-connection-by-at-scact-via-mbpl-r20-driver/24130): > > Here is an example to establish data connection by AT!SCACT via MBPL R20 driver: Module: WP7609 FW: R13 MBPL: R20 PC Environment: Ubuntu 18 need to install the MBPL R20 driver for qmi\_wwan and qcserial (MBPL\_Drivers\_USB\_R20\_ENG1-src.tar.gz) avoid the Ubuntu changing the network name: ln -s /dev/null /etc/systemd/network/99-default.link sudo apt-get install libqmi-utils sudo apt-get install udhcpc now insert the USB to PC sudo chmod 777 /sys/class/net/wwan0/qmi/raw\_ip … ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 11:32am UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/3 "2022-11-04T11:32:26Z")
Hello Jyijyi, I haven’t tried latest firmware and i don’t think it will be very usefull since everythink works fine with mbim-network command (which i don’t want to use). Here is the result of the command you asked me to try (this command is not defined in the official AT documentation for this the MC7455 modem ?) ```auto AT!SCACT? !SCACT: 1,0 OK ``` And when i try to start the data connection i get : ```auto AT!SCACT=1,1 +CME ERROR: no network service ``` Do you know where this error might come from ? NB: My apn has no password nor username that need to be set ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 4, 2022, 11:47am UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/4 "2022-11-04T11:47:43Z")
What driver are you using? Did you follow the document to install mbpl driver? Btw, your fw seems to be a bit old ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 1:53pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/5 "2022-11-04T13:53:24Z")
Sorry for the late reply, i’m currently upgrading everything i’ll tell you when all is ready. My driver is actually ModemManager, i’m going to install mbpl instead as you said and come back to you as soon as possible ! (At the moment i’m upgrading the fw to the last version) ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 4, 2022, 2:21pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/6 "2022-11-04T14:21:53Z")
For using at!scact, you also need to use rmnet in at!usbcomp ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 4:12pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/7 "2022-11-04T16:12:21Z")
So far I’ve successfully upgraded my fw version to the latest version : ```auto ati3 Manufacturer: Sierra Wireless, Incorporated Model: MC7455 Revision: SWI9X30C_02.38.00.00 rE3F3E55C03AE94 jenkins 2022/01/13 05:16:00 MEID: 35907206211218 IMEI: 359072062112186 IMEI SV: 22 FSN: LQ817273680410 +GCAP: +CGSM ``` I also update usbcomp to use rmnet : ```auto at!usbcomp? Config Index: 1 Config Type: 1 (Generic) Interface bitmask: 0000010D (diag,nmea,modem,rmnet0) ``` I was trying to install mbpl but i can’t find a version matching my linux kernel 4.16.18+ Yet, why do use recommand to install this driver since i am directly sending at commands to the serial port so if i understand well, we don’t need an external software to help the communication between the OS and the modem ? I really thank you for your help ! By the way, after updating the fw version, my at serial port changed from ttyUSB3 to ttyUSB4. Do you know why this appended ? Is it possible to change the serial port used to communicate with at commands with the modem (if i wanted to use ttyUSB3 again) ? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 4, 2022, 4:23pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/8 "2022-11-04T16:23:18Z")
will it enumerate /dev/ttyUSB3 after reboot? You can try the old GOBI driver which should supports your kernel: [https://source.sierrawireless.com/resources/airprime/software/usb-drivers-linux-qmi-software-s2,-d-,42n2,-d-,64/#sthash.P1pqZyA7.dpbs](https://source.sierrawireless.com/resources/airprime/software/usb-drivers-linux-qmi-software-s2,-d-,42n2,-d-,64/#sthash.P1pqZyA7.dpbs) But you need to black list the qcserial and qmi\_wwan driver if you use the Gobi driver. e.g. add the following to the “/etc/modprobe.d/blacklist-modem.conf” file in Ubuntu PC and restart the host : blacklist qcserial blacklist qmi\_wwan ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 5:06pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/9 "2022-11-04T17:06:08Z")
To answer your question, here is the output of dmesg command regarding ttyUSB serial ports enumeration ```auto [5.304644] usb 2-2: Qualcomm USB modem converter now attached to ttyUSB2 [5.305834] usb 2-2: Qualcomm USB modem converter now attached to ttyUSB3 [5.307015] usb 2-2: Qualcomm USB modem converter now attached to ttyUSB4 ``` /dev/ttyUSB3 port is enumerated (so i don’t know why at command are not supported by ttyUSB3 instead) About the mbpl driver, I built it from source on my kernel so i don’t use GOBI I mooved the kernel files generated : - qcserial.ko - qmi\_wwan.ko - usb\_wwan.ko to /lib/modules/4.16.18+/kernel/drivers/net/usb/ and ran the following commands : ```auto depmod 4.16.18+ update-initramfs -c -k 4.16.18+ reboot ``` I tried to follow the next steps on your thread here [Example on establishing data connection by AT!SCACT via MBPL R20 driver](https://forum.sierrawireless.com/t/example-on-establishing-data-connection-by-at-scact-via-mbpl-r20-driver/24130) ```auto qmicli --device=/dev/cdc-wdm0 --wds-noop --client-no-release-cid ``` But i have no cdc interface so the command fails Yet, dmesg tells me a cdc-wdm interface has been registered : ```auto [5.323756] usbcore: registered new interface driver cdc_wdm ``` ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 4, 2022, 5:19pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/10 "2022-11-04T17:19:20Z")
You can try to disable the nmea port in at!usbcomp and see of ttyusb3 is the AT port ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 5:24pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/11 "2022-11-04T17:24:26Z")
By the way here is a little update of information after all this changes : ```auto at+cgdcont? +CGDCONT: 1,"IP","mobiledata","0.0.0.0",0,0,0,0 OK at!gstatus? !GSTATUS: Current Time: 5693 Temperature: 44 Reset Counter: 26 Mode: ONLINE System mode: WCDMA PS state: Not attached WCDMA band: WCDMA 2100 WCDMA channel: 10762 GMM (PS) state:NULL --- MM (CS) state: IDLE NORMAL SERVICE WCDMA L1 state:L1M_PCH_SLEEP LAC: 0EA6 (3750) RRC state: DISCONNECTED UTRAN Cell ID: 04721433 (74585139) RxM RSSI C0: -94 RxD RSSI C0: --- RxM RSSI C1: --- RxD RSSI C1: --- at+cops=? +cops: (1,"005400300035003400300030","00540030","20815",7),(2,"005400300035003400300030","00540030","20815",2),(1,"004600300034003600300030","00420030","20820",) OK OK at+cops? +cops: 0,0,"005400300",2 OK at!impref? !IMPREF: preferred fw version: 02.38.00.00 preferred carrier name: GENERIC preferred config name: GENERIC_002.082_000 preferred subpri index: 000 current fw version: 02.38.00.00 current carrier name: GENERIC current config name: GENERIC_002.082_000 current subpri index: 000 OK ``` ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 5:29pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/12 "2022-11-04T17:29:36Z")
Your solution of disabling nmea worked to change from usage of ttyUSB4 to ttyUSB3 regarding AT commands 😃 Still what should i do next about the disappearance of /dev/cdc-wdm0 interface ? Again I deeply thank you for your support ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 5:40pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/13 "2022-11-04T17:40:12Z")
Little edit, Rigth after the resgitered interface driver cdc\_wdm message i encounter an error with qmi\_wwan version : ```auto [4.708399] usbcore: registered new interface driver cdc_wdm [4.720879] qmi_wwan: version magic '4.16.18 SMP preempt mod_unload ' should be '4.16.18+ SMP preempt mod_unload ``` ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 4, 2022, 5:44pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/14 "2022-11-04T17:44:41Z")
Seems you don’t use the same kernel version to compile qmi\_wwan ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 4, 2022, 5:47pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/15 "2022-11-04T17:47:33Z")
Yup i just removed it and recompiled from source (maybe i had duplicate from a previous action?). ---
**Author:** ![dl5162](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/dl5162/32/2169_2.png) [@dl5162](https://forum.sierrawireless.com/u/dl5162)\ **Post date:** [November 4, 2022, 6:11pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/16 "2022-11-04T18:11:58Z")
> [@pierrem](#): > > NB: I’m able to reach internet from the modem interface when i use mbim-network command and then configure my network as above but my goal is to use AT commands instead of mbim-network program ! Not sure that works. There is no way to specify the MBIM Session ID using AT commands. OK, it might default to session 0, so that it works for connecting one APN. You failed to configure any routes in your setup. Does it work if you do?: ```auto ip route add default dev wwp0s20f0u2i12 ``` Netmask and gateway addresses are just artificial anyway. The network assigned address is a /32. And there is no ARP with MBIM, so faking a gateway address is pointless. ---
**Author:** ![dl5162](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/dl5162/32/2169_2.png) [@dl5162](https://forum.sierrawireless.com/u/dl5162)\ **Post date:** [November 4, 2022, 6:18pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/17 "2022-11-04T18:18:06Z")
FWIW, I believe the default qmi\_wwan and cdc\_mbim drivers in 4.16.18 should work just fine wth the MC7455 modem. Ruuning around replacing drivers is not likely to change the AT command interface behaviour of the modem firmware. But what do I know… ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [November 5, 2022, 1:31am UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/18 "2022-11-05T01:31:38Z")
you should see something like this in dmesg: ```auto [1294.123026] usb 4-1: New USB device found, idVendor=1199, idProduct=9091 [1294.123027] usb 4-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [1294.123029] usb 4-1: Product: Sierra Wireless EM7511 Qualcomm® Snapdragon™ X16 LTE-A [1294.123030] usb 4-1: Manufacturer: Sierra Wireless, Incorporated [1294.123031] usb 4-1: SerialNumber: YT22174335011234 [1294.272992] usbcore: registered new interface driver usbserial [1294.273007] usbcore: registered new interface driver usbserial_generic [1294.273016] usbserial: USB Serial support registered for generic [1294.312564] usbcore: registered new interface driver cdc_wdm [1294.314167] qmi_wwan: loading out-of-tree module taints kernel. [1294.314239] qmi_wwan: module verification failed: signature and/or required key missing - tainting kernel [1294.318354] qmi_wwan 4-1:1.8: cdc-wdm0: USB WDM device [1294.319261] qmi_wwan 4-1:1.8 wwan0: register 'qmi_wwan' at usb-0000:03:00.0-1, WWAN/QMI device, 76:26:57:5f:8c:0b [1294.321894] usbcore: registered new interface driver qmi_wwan [1294.327436] usbcore: registered new interface driver qcserial [1294.327445] usbserial: USB Serial support registered for Qualcomm USB modem [1294.327453] usbserial: USB Serial support registered for Qualcomm USB modem [1294.331511] qcserial 4-1:1.0: Qualcomm USB modem converter detected [1294.331671] usb 4-1: Qualcomm USB modem converter now attached to ttyUSB0 [1294.333676] qcserial 4-1:1.2: Qualcomm USB modem converter detected [1294.333945] usb 4-1: Qualcomm USB modem converter now attached to ttyUSB1 [1294.351996] qcserial 4-1:1.3: Qualcomm USB modem converter detected [1294.352243] usb 4-1: Qualcomm USB modem converter now attached to ttyUSB2 owner@ubuntu:~$ owner@ubuntu:~$ ls /dev/cdc-wdm0 /dev/cdc-wdm0 ``` ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 7, 2022, 3:12pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/19 "2022-11-07T15:12:39Z")
Hello jyijyi ! Sorry for answering so lately (i was out for the weekend and also tried to figure out the solution myself) After a lot of problems regarding system configuration, kernel, understanding, etc… i finally got the modem interface reaching Internet using qmicli and AT!SCACT command. So here is my actual setup : ```auto at+creg? +CREG: 1,1 OK at+cgatt? +CGATT: 1 OK at+cgact? +CGACT: 1,1 OK at!scact? !SCACT: 1,0 OK at+cgcontrdp +CGCONTRDP: 1,5,mobiledata,10.138.217.108,,176.241.248.113,176.241.248.114 OK ``` I installed last version of mbpl (R28), libqmi-utils and udhcpc according to one of your post I had to run the following command to connect the mobile network : ```auto qmicli -p -d /dev/cdc-wdm0 --device-open-net='net-raw-ip|net-no-qos-header' --wds-start-network="apn='mobiledata',',ip-type=4" --client-no-release-cid ``` Else udhcpc discover was sending request over and over Yet all this brings me back to my initial state when i was using mbim-network. So what do qmcli or mbim-network that i can’t do with AT commands only ? And also, what is the purpose of using qmicli instead of mbim-network since i could make it works with mbim ? The reason why i didn’t want to use mbim-network anymore is that with some operators, i encountered several problems setting up LTE connections. That’s why i wanted to rely on AT commands only so i would control each steps to setup the connection and be able to know where my configuration fails rather than relying on a software that i don’t understand all the features. ---
**Author:** ![pierrem](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@pierrem](https://forum.sierrawireless.com/u/pierrem)\ **Post date:** [November 7, 2022, 3:14pm UTC](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283/20 "2022-11-07T15:14:27Z")
Hello dl5162, Thank you very much for your feedback ! I really appreciate it ! I agree with you but i succeed in setuping my system with jyijyi’s requirements so it’s ok 😉 [Next page](https://forum.sierrawireless.com/t/mc7455-connection-sequence-to-lte-network/28283.md?page=2)