Quick and dirty code to read and send SMS messages for Huawei EC122 CDMA Modem. Might be buggy, use with caution.

smsreader_ec122.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Copyright (c) 2022, Wei Mingzhi <whistler_wmz@users.sf.net>.
# SPDX-License-Identifier: BSD-3-Clause
# https://spdx.org/licenses/BSD-3-Clause.html
#
# Quick and dirty code to read and send SMS messages for Huawei EC122 CDMA Modem.
#
# Most likely this will NOT work with any other GSM/CDMA phones/modems, as the AT
# commands of Huawei EC122 seem different from Nokia's or any other GSM modems.
#
# Please use a better solution like Gammu for supported modems:
# https://wammu.eu/

import serial
import sys
import re

import logging
logging.basicConfig(level=logging.INFO, format='%(levelname)-8s %(message)s')

def _write_cmd(ser, cmd):
    logging.debug('writing command: ' + cmd)
    cmd = ('AT' + cmd).encode('ascii') + serial.CR + serial.LF
    ser.write(cmd)

def _get_line(ser):
    line = b''
    line_began = False
    while True:
        ch = ser.read(size=1)
        if not line_began:
            if ch == serial.CR or ch == serial.LF:
                continue
            line_began = True
        if ch == serial.CR:
            ser.read(size=1) # skip LF
            return line.decode('ascii')
        line += ch
    return line

def _unlock_pin(ser, pin):
    _write_cmd(ser, '^CPIN="' + pin + '"')
    while True:
        line = _get_line(ser)
        if line.startswith('OK'):
            logging.debug('PIN unlocked')
            break
        elif line.startswith('+CMS ERROR'):
            logging.error('PIN unlock error, exiting immediately to avoid SIM locking!!! ' + line)
            sys.exit(255)

def read_all_sms_ec122(port, delete_sms=False, pin=None):
    ser = serial.Serial(port=port, baudrate=19200)
    try:
        if pin is not None:
            _unlock_pin(ser, pin)
        sms_list = []
        sms_text_list = []
        logging.debug('getting sms list...')
        _write_cmd(ser, '^HCMGL')
        while True:
            line = _get_line(ser)
            if line.startswith('^HCMGL'):
                line_split = re.split('[:,]', line)
                index = int(line_split[1])
                sms_list.append(index)
            elif line.startswith('+CMS ERROR'):
                logging.error('get sms list error: ' + line)
                return None
            elif line.startswith('OK'):
                break
         
        for index in sms_list:
            _write_cmd(ser, '^HCMGR=' + str(index))
            while True:
                line = _get_line(ser)
                if line.startswith('^HCMGR'):
                    line_split = re.split('[:,]', line)
                    (dummy, caller_id, year, month, day, hour, minute, second, lang, fmt, length, v3, v4, v5, v6) = line_split
                    sms_data = ser.read(size=int(length))
                    ser.read(size=3) # skip ^Z CR LF
                    fmt = int(fmt)
                    if fmt == 1:
                        sms_text = sms_data.decode('ascii')
                    elif fmt == 6:
                        sms_text = sms_data.decode('utf-16be')
                    else:
                        logging.info('unsupported sms format, skipping: ' + str(fmt))
                        break
                    stat_line = _get_line(ser)
                    if stat_line != 'OK':
                        logging.error('ending line is not OK: ' + stat_line)
                    else:
                        s = {}
                        s['Number'] = caller_id
                        s['Text'] = sms_text
                        s['DateTime'] = (int(year), int(month), int(day), int(hour), int(minute), int(second))
                        sms_text_list.append(s)
                    break
         
        if delete_sms:
            for index in sms_list:
                _write_cmd(ser, '+CMGD=' + str(index))
                while True:
                    line = _get_line(ser)
                    if line.startswith('OK'):
                        logging.debug('SMS deleted: ' + str(index))
                        break
                    elif line.startswith('+CMS ERROR'):
                        logging.error('SMS delete error: ' + str(index))
                        break
        return sms_text_list
    finally:
        ser.close()

def send_sms_ec122(port, dest, text, pin=None):
    ser = serial.Serial(port=port, baudrate=19200)
    try:
        if pin is not None:
            _unlock_pin(ser, pin)
        _write_cmd(ser, '^HCMGS="' + dest + '"')
        ser.write(text.encode('utf-8'))
        ser.write(int(26).to_bytes(1, 'big'))
        while True:
            line = _get_line(ser)
            if line.startswith('+CMS ERROR'):
                logging.error('send sms error: ' + line)
                break
            elif line.startswith('OK'):
                logging.info('send sms ok')
                break
    finally:
        ser.close()