In order to enable support for the SIMCOM SIM7600 modem a single line patch is needed to one of the kernel modules, we have prepared a fully automated script that when run will download, patch, compile and install the module for kernel 4.9.80

Once completed any temporary source files can be removed

# cd /root/
# wget --no-check-certificate 'https://drive.google.com/uc?export=download&id=1SLjszmq6G9Z8s-zPsWg2weV4dYfvEUR0' -O qmi-update.tar.gz
# tar -xzf qmi-update.tar.gz
# chmod +x qmi-update.sh
# ./qmi-update.sh

On reboot you will notice the new kenel module is loaded and the modem will now respond to qmi interface calls :

[ 5.130501] qmi_wwan: loading out-of-tree module taints kernel.
[ 5.134831] qmi_wwan 1-1.4:1.5: cdc-wdm0: USB WDM device
[ 5.137514] qmi_wwan 1-1.4:1.5 wwan0: register 'qmi_wwan' at usb-3f980000.usb-1.4, WWAN/QMI device, ba:7c:bc:a7:0d:d5
[ 5.137698] usbcore: registered new interface driver qmi_wwan
[ 5.146165] usbcore: registered new interface driver option
[ 5.146267] usbserial: USB Serial support registered for GSM modem (1-port)
[ 5.147263] option 1-1.4:1.0: GSM modem (1-port) converter detected
[ 5.150019] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 5.168171] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB1
[ 5.168798] option 1-1.4:1.1: GSM modem (1-port) converter detected
[ 5.170376] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB2
[ 5.171092] option 1-1.4:1.2: GSM modem (1-port) converter detected
[ 5.175605] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB3
[ 5.187888] option 1-1.4:1.3: GSM modem (1-port) converter detected
[ 5.188542] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB4
[ 5.189047] option 1-1.4:1.4: GSM modem (1-port) converter detected
[ 5.189595] usb 1-1.4: GSM modem (1-port) converter now attached to ttyUSB5

root@raspberrypi:~# qmicli  --nas-get-signal-strength  -d /dev/cdc-wdm0
[/dev/cdc-wdm0] Successfully got signal strength
Current:
        Network 'lte': '-88 dBm'
RSSI:
        Network 'lte': '-88 dBm'
ECIO:
        Network 'lte': '-2.5 dBm'
IO: '-106 dBm'
SINR: (8) '9.0 dB'
RSRQ:
        Network 'lte': '-10 dB'
SNR:
        Network 'lte': '7.6 dB'
RSRP:
        Network 'lte': '-109 dBm'

Note SIM7600 is a Raw-IP Mode Modem

Further due to the modem not supporting AT*CNTI AT commands modemstat will not be able to show which service the modem is using correctly.

root@raspberrypi:~# modemstat
SIM status                         : SIM unlocked and ready
Signal Quality                     : 15/32    (Bit error rate cannot be determined)
Network Registration               :  ** Infomation Not Available **
Registration state                 : Not registered, searching for network
GPRS/EDGE/UMTS/HSDPA Availability  : NONE

GPRS/EDGE/UMTS/HSDPA Mode Status   : NONE

Manufacturer: SIMCOM INCORPORATED
Model: SIMCOM_SIM7600E-H
Revision: SIM7600M22_V1.1
IMEI: 86758XXXXXXXX90
+GCAP: +CGSM

Instead You can use AT+CPSI? To request status from module:

AT+CPSI? 

+CPSI: LTE,Online,240-02,0x07E5,137012738,260,EUTRAN-BAND7,3000,3,3,-104,-892,-619,20