RPi - SMS to Mail with Raspberry Pi and ZTE MF823 Surfstick
(posted 2019.09.12, last updated 2020.05.21)

Goal

I want my Raspberry Pi Zero W to receive SMS on a spare SIM card / contract / number and send the contents to my mail account. Use case: some web services require your mobile number for registration but I do not like to give them my main number.

Update: Decided to try to use my OpenWRT instead of the Raspberry.

Update2: Fixed some issues with Modem switching from ttyUSB2 to ttyUSB3 and back.

Steps

Setup USB-Surf-Stick ZTE MF823

The Surf-Stick is in network mode by default, in this mode no serial devices ttyUSB are offered (Other Surf-Sticks offer the modem directly by default). Sending/Receiving SMS could be handled using the web interface (as an API), but I would prefer to directly access the modem. The device can be put in modem mode and then gammu can be used to access it. Unfortunately, receiving SMS did not work at first, while sending was working well. Luckily, while experimenting I realized that changing the Preferred Message Storage solved that.

Connect Surf-Stick to your PC (due to headless RPi)
Disconnect and Disable automatic connection
- Browse to 192.168.0.1
- "Home" > "Disconnect"
- "Settings" > "Network Settings" > "Dial-Up Settings" > Change Auto to Manual, Save
Switch form network to modem (factory) mode:
http://192.168.0.1/goform/goform_process?goformId=MODE_SWITCH&switchCmd=FACTORY
Test if stick is in modem mode (on Linux)
- dmesg should list multiple GSM modem (1-port) converter now attached to ttyUSB0-2
- ls -la /dev/ttyUSB* should list 3 devices
- lsusb should list ID 19d2:0016 ZTE WCDMA Technologies MSM
Change Preferred Message Storage (as i was not able to receive sms but send them)
- Disable ModemManager: systemctl stop ModemManager.service
- Open serial connection: socat - /dev/ttyUSB2,crnl
- Change Preferred Message Storage to message storage area on the SIM card:
```
AT+CPMS="SM","SM","SM"
```

Setup SIM

Disable PIN on SIM card:
I disabled the PIN in order to have it easier to configure, should be possible with PIN, but you have to change some configurations.

Setup RPi Software

Insert SD, Boot RPi, connect via ssh

Setup the modem software

Installation:

sudo apt-get install usb-modeswitch usb-modeswitch-data
sudo apt-get install gammu
sudo adduser --system gammu --disabled-login --no-create-home
sudo adduser gammu dialout

Configuration:
/etc/gammurc

[gammu]
device = /dev/ttyUSB2
name = ZTE MF823 LTE USB-SurfStick
connection = at
use_locking = yes
LogFile = /var/log/gammu
#LogFormat = textalldate
LogFormat = errorsdate

Test gammu:
- gammu identify
- Send SMS: gammu sendsms TEXT 0123456789 -text "Test Message"
- Receive SMS: gammu getallsms

Setup modem service:

Installation: sudo apt-get install gammu-smsd

Configuration:
/etc/gammu-smsdrc

[gammu]
device = /dev/ttyUSB2
name = ZTE MF823 LTE USB-SurfStick
connection = at
use_locking = yes
LogFile = /var/log/gammu
#LogFormat = textalldate
LogFormat = errorsdate

[smsd]
service = files
LogFile = /var/log/gammu
#DebugLevel = 4
DebugLevel = 0
CheckSecurity = 0
CheckBattery = 0

inboxpath = /var/spool/gammu/inbox/
outboxpath = /var/spool/gammu/outbox/
sentsmspath = /var/spool/gammu/sent/
errorsmspath = /var/spool/gammu/error/

RunOnReceive = /usr/local/bin/smsin.sh

(Re)Start gammu-smsd service: systemctl restart gammu-smsd

Setup mail (uses external SMTP)

Installation: apt-get install ssmtp mailutils

Configuration: /etc/ssmtp/ssmtp.conf

root=system@mydomain.tld
mailhub=mail.mydomain.tld:587
FromLineOverride=YES
AuthUser=system@mydomain.tld
AuthPass=SOMEPASSWORD
UseTLS=Yes
UseSTARTTLS=Yes

Setup SMS forwarding to mail:
/usr/local/bin/smsin.sh

#!/bin/bash
for i in $(seq $SMS_MESSAGES) ; do
    eval printf \"SMS Service: New SMS\\nSender: \${SMS_${i}_NUMBER}\\n----\\n\${SMS_${i}_TEXT}\" | \
    mail -s "SMS Service: New SMS" -aFrom:system@mydomain.tld mymail@mydomain.tld
    logger -t smsd "SMS forwarded by mail."
done

Alternatively: Setup OpenWRT Software

The issues with ttyUSB lead me back to a RPi configuration...

Adjustments

opkg install kmod-usb-serial usbutils

/etc/rc.local

echo "19d2 0016" > /sys/bus/usb-serial/drivers/generic/new_id

Setup the SMS software

Installation:
```
opkg install gammu
```

/etc/config/gammu

config daemon default
        option enabled          1
        option device           /dev/ttyUSB2
        option connection       at
        option logfile          syslog
        option onreceive        /etc/smsin/smsin.sh
        option onerror          /etc/smsin/onfailure.sh
        option send             False

/etc/init.d/gammu - Add following line after the line with "checkbattery" in it:

echo -e "CheckSecurity = 0" >> $conffile
echo -e "ReceiveFrequency = 60" >> $conffile
echo -e "StatusFrequency = 60" >> $conffile
echo -e "CommTimeout = 60" >> $conffile
echo -e "SendTimeout = 60" >> $conffile
echo -e "LoopSleep = 10" >> $conffile
#echo -e "ResetFrequency = 3600" >> $conffile

Setup Mail and SMS forwarding to mail:

Install

opkg install mailsend

/etc/smsin/smsin.sh

#!/bin/ash
for i in $(seq $SMS_MESSAGES) ; do
        eval printf \"Sender: \${SMS_${i}_NUMBER}\\n\\n\${SMS_${i}_TEXT}\" | \
        mailsend \
                -smtp smtp.mydomain.tld \
                -port 587 \
                -starttls \
                -auth-login \
                -user system@mydomain.tld \
                -pass SOMEPASSWORD \
                -t mymail@mydomain.tld \
                -f system@mydomain.tld \
                -sub "SMS Service: New SMS"
        logger -t smsd "SMS forwarded by mail."
        rm /var/sms/inbox/$1
done

Update2: Fixed issue with ttyUSB*

The following did not help, still searching for a solution...

Had some issues where the modem switched from ttyUSB2 to ttyUSB3 and thereby gammu loosing connection

Someone had the same problem and I was able to use the solution posted there: (de) https://forum-raspberrypi.de/forum/thread/46635-warum-disconnected-gsm-modem-zte-mit-gammu-gesteuert-alle-2-stunden/

However, I had to adapt the solution, as there is no udev functionality for OpenWRT. Sadly, it is just a hack, as the PRODUCT/VENDOR code is the same for all ttyUSB0,1,2/3 that are created by the stick, so I just hope that either 2 or 3 is the one I want to access....

/etc/hotplug.d/tty/10-lte-modem

SYMLINK="lte-modem"
case "${DEVICENAME}" in
  ttyUSB2|ttyUSB3)
    if [ "${ACTION}" = "add" ]; then
      logger -t hotplug "<tty> Added LTE Modem: ${DEVICENAME}"
      ln -s /dev/${DEVICENAME} /dev/${SYMLINK}
    fi
    if [ "${ACTION}" = "remove" ]; then
      logger -t hotplug "<tty> Removed LTE Modem: ${DEVICENAME}"
      rm /dev/${SYMLINK}
    fi
    ;;
esac

/etc/config/gammu

[...]
option device           /dev/lte-modem
[...]

Enable Cron for periodic restart of gammu:

/etc/init.d/cron start
/etc/init.d/cron enable

/etc/smsin/cron.sh

    #!/bin/ash
    /etc/init.d/gammu restart

crontab -e
```
    0 * * * * /etc/smsin/cron.sh
```

References

Raspberry Pi - Receive/Send SMS (gammu)

Switch ZTE Surfstick to Modem Mode (instead of Network Mode which offers no serial USB interface)

SMS / CPMS Info

(en) https://www.developershome.com/sms/cpmsCommand.asp (Archive)

ZTE AT Commands

ZTE use SMS using calls to the URL interface

(en) https://weekly-geekly.github.io/articles/277637/index.html (Archive)

ZTE + OpenWRT

(en) https://technicalexperiments.wordpress.com/2015/10/30/zte-mf831-for-use-with-openwrt-serial-modem-instead-of-cdc_ether/comment-page-1/#comments (Archive)

Gammu + OpenWRT