send-sms.py

#!/usr/bin/env python3

import sms
import re
import sys
import argparse
import codecs

parser = argparse.ArgumentParser()
requiredNamed = parser.add_argument_group('required named arguments')
requiredNamed.add_argument(
    "-t", "--text", help="Text content", required=True)
requiredNamed.add_argument(
    "-m", "--msisdn", help="MSISDN reciever, 46XXXXXXXXX", required=True)
requiredNamed.add_argument(
    "-s", "--serial_interface", help="Serial interface", required=True)
args = parser.parse_args()

text = args.text.encode().replace(b'\\n', b'\n').decode()
msisdn = args.msisdn
serialInterface = args.serial_interface

if re.match(r'^46[1-9]\d{8}$', msisdn):
    sms.send(text=text, msisdn=msisdn, serialInterface=serialInterface)
else:
    print('ERROR: Not a correct swedish number')
    sys.exit(1)

sms.py

#!/usr/bin/env python3

import serial
import smsutil


class smsInitiateError(LookupError):
    pass


class smsMisdnError(LookupError):
    pass


class smsSendError(LookupError):
    pass


class smsModemConnectionError(LookupError):
    pass


def send(text, msisdn, serialInterface):
    try:
        with serial.Serial(serialInterface, 115200, timeout=4) as modem:

            modem.write(b'AT+CMGF=1\r')
            response = modem.read(16)
            if b'OK' not in response:
                raise smsInitiateError('FAILED: AT+CMGF=1')

            modem.write(b'AT+CSCS="GSM"\r')
            response = modem.read(20)
            if b'OK' not in response:
                raise smsInitiateError('FAILED: AT+CSCS="GSM"')

            msisdn = msisdn.encode()
            writeData = b'AT+CMGS="'+msisdn+b'"\r'
            modem.write(writeData)
            response = modem.read(25)
            if b'>' not in response:
                raise smsMisdnError('FAILED: '+str(writeData.decode()))

            data = smsutil.encode(text)
            dataLength = len(data)+4
            modem.write(data)
            modem.write(bytes([26]))
            response = modem.read(dataLength+18)
            if b'OK' not in response[dataLength:]:
                raise smsSendError('FAILED: To send message "'+text+'"')

    except serial.serialutil.SerialException:
        raise smsModemConnectionError(
            'FAILED: To initiate modem serial connection with "' +
            serialInterface + '"')