====== Hands On LTE on OpenWrt ======
===== Supported hardware =====
  * The supported LTE hardware in OpenWrt can be a minefield and my recommendation is to stick with those hardware that have been tested by the community to be confirmed working.
  * In the past I tried to use a Huawei LTE USB stick. 
  * They can be running in two modes.
        * **RNDIS**  https://openwrt.org/docs/guide-user/network/wan/wwan/ethernetoverusb_rndis
        * **NCM**  https://openwrt.org/docs/guide-user/network/wan/wwan/ethernetoverusb_ncm
  * The preferred mode is **NCM** but the with USB stick I had it was impossible to switch modes and I was stuck with **RNDIS** mode.
  * Another time I had a Mikrotik Access Point flashed with OpenWrt that had one of their LTE modems (pcie card). After many days of trying various things I eventually just gave up and replaced the card with one that has proper OpenWrt support.
  * Some Access Points that comes with LTE modems included are well supported in OpenWrt.
        * Cell-C / Belotech (https://openwrt.org/toh/cell_c/rtl30vw)
        * GL.iNet GL-MiFi (https://openwrt.org/toh/gl.inet/gl-mifi)

===== Packages to include =====
  * To get the LTE modem working in OpenWrt you need to include some specific packages.
  * There are also some optional packages that you can include since they come in handy.
==== Required ====
  * kmod-usb-wdm
  * kmod-usb-net
  * kmod-usb-net-qmi-wwan
  * libqmi
  * uqmi
  * kmod-mii
<code bash>
opkg update
opkg install kmod-mii kmod-usb-net kmod-usb-wdm kmod-usb-net-qmi-wwan uqmi
</code>
For Serial Support (AT Commands)
  * kmod-usb-serial
  * kmod-usb-serial-option
  * kmod-usb-serial-wwan
<code bash>
opkg update
opkg install kmod-usb-serial-option kmod-usb-serial kmod-usb-serial-wwan
</code>

==== Optional ====
  * qmi-utils
  * picocom
  * luci-proto-qmi
<code bash>
opkg update
opkg install picocom qmi-utils uci-proto-qmi
</code>

 

===== Interacting with the modem =====
  * After you installed the packages reboot the Access Point.
  * If everything works as intended you should see the following device
<code bash>
ls -l /dev/cdc-wdm0
</code>
  * Now you can try to interact with the modem.
<code bash>
uqmi -d /dev/cdc-wdm0 --get-data-status
#This is the return
"connected"

uqmi -d /dev/cdc-wdm0 --get-signal-info
#This is the return
{
	"type": "lte",
	"rssi": -69,
	"rsrq": -11,
	"rsrp": -96,
	"snr": 11.000000
}

uqmi -d /dev/cdc-wdm0 --get-system-info
#This is the return
{
	"wcdma": {
		"service_status": "none",
		"true_service_status": "none",
		"preferred_data_path": false
	},
	"lte": {
		"service_status": "available",
		"true_service_status": "available",
		"preferred_data_path": false,
		"domain": "cs-ps",
		"service": "cs-ps",
		"roaming_status": "off",
		"forbidden": false,
		"mcc": "655",
		"mnc": "07",
		"tracking_area_code": 18,
		"enodeb_id": 18353,
		"cell_id": 80,
		"voice_support": true,
		"ims_voice_support": false,
		"cell_access_status": "all calls",
		"registration_restriction": 0,
		"registration_domain": 0
	}
}
</code>

===== UCI Configuration =====
  * The UCI system includes support for LTE confguration in ///etc/config/network//.
  * The MESHdesk firmware will create the config section based on the configuration returned by the controller.
  * Here is a sample section as reference
<code bash>
config interface 'wwan'
	option ifname 'wwan'
	option disabled '0'
	option wan_bridge '0'
	option device '/dev/cdc-wdm0'
	option apn 'lte.broadband.is'
	option proto 'qmi'
	option auth 'none'
</code>
  * You can also install the **luci-proto-qmi** package which essentially does the same that MESHdesk and APdesk does but only local on the Access Point. 


===== Using AT Commands =====
  * We can use picocom terminal to reach the LTE modem
<code bash>
 picocom /dev/ttyUSB2
</code>
  * I had to first issue the following commands before the modem returned something for CUSD
<code bash>

AT+CMGF=1
OK
ATZ
OK
AT+CUSD=1,"*101#",15
OK

+CUSD: 0,"Balance: R 0.00 .Data: 25.83 MB.",15

</code>
  * You can allos issue the following command without needing to log into picocom
<code bash>
 echo 'AT+CUSD=1,"*101#",15' | picocom -qrix 10000 /dev/ttyUSB2
#Here is what my provider returned
+CUSD: 0,"Balance: R 0.00 .Data: 6.40 MB.",15
</code>