to see send sms using At command this will help.
    import serial
    import time
    class TextMessage:
        def __init__(self, recipient="+2348065777685", message="TextMessage.content not set."):
            self.recipient = recipient
            self.content = message
        def setRecipient(self, number):
            self.recipient = number
        def setContent(self, message):
            self.content = message
        def connectPhone(self):
            self.ser = serial.Serial('COM70', 460800, timeout=5, xonxoff = False, rtscts = False, bytesize = serial.EIGHTBITS, parity = serial.PARITY_NONE, stopbits = serial.STOPBITS_ONE)
            time.sleep(1)
        def sendMessage(self):
            self.ser.write('ATZ\r')
            time.sleep(1)
            self.ser.write('AT+CMGF=1\r')
            time.sleep(1)
            self.ser.write('''AT+CMGS="''' + self.recipient + '''"\r''')
            time.sleep(1)
            self.ser.write(self.content + "\r")
            time.sleep(1)
            self.ser.write(chr(26))
            time.sleep(1)
        def disconnectPhone(self):
            self.ser.close()
    sms = TextMessage("+2348063796720","Mummy i sent this message from my computer")
    sms.connectPhone()
    sms.sendMessage()
    sms.disconnectPhone()
    print "message sent successfully"
To recieve sms using At command this should help
    import serial
    import time
    import sys
    class HuaweiModem(object):
        def __init__(self):
            self.open()
        def open(self):
            self.ser = serial.Serial('COM70', 406800, timeout=5)
            self.SendCommand('ATZ\r')
            self.SendCommand('AT+CMGF=1\r')
        def SendCommand(self,command, getline=True):
            self.ser.write(command)
            data = ''
            if getline:
                data=self.ReadLine()
            return data 
        def ReadLine(self):
            data = self.ser.readline()
            print data
            return data 
        def GetAllSMS(self):
            self.ser.flushInput()
            self.ser.flushOutput()
            command = 'AT+CMGL="REC UNREAD"\r\n'#gets incoming sms that has not been read
            print self.SendCommand(command,getline=True)
            data = self.ser.readall()
            print data
    h = HuaweiModem()
    h.GetAllSMS()