How to reject or accept an incoming call to my GSM modem using AT commands in Python? -

i've wrote below python program wait incoming calls , accept or reject them. based on this document , this document, appropriate @ commands accept incoming call ata or ats0 or ats0<n>. , appropriate commands reject incoming call ath or at h.

i tried above commands, incoming call neither answered nor rejected!

my python program :

import time import serial  phone = serial.serial("com10",  115200, timeout=5)  try:     time.sleep(1)      while(1):         x = phone.readline()         print(x)         if (x == b'ring\r\n'):             phone.write(b'at h') # replaced 'at h' above                                  # commands, nothing changed                                  # incoming call. ringing.             time.sleep(2)  finally:     phone.close() 

results at h:

>>> ================================ restart ================================ >>>  b'' b'' b'\r\n' b'ring\r\n' b'at h\r\n' b'ring\r\n' b'at h\r\n' b'ring\r\n' b'at h\r\n' b'ring\r\n' b'at h\r\n' b'ring\r\n' 

results ath:

>>> ================================ restart ================================ >>>  b'' b'' b'' b'\r\n' b'ring\r\n' b'ath\r\n' b'ring\r\n' b'ath\r\n' b'ring\r\n' b'ath\r\n' b'ring\r\n' 

results ata:

>>> ================================ restart ================================ >>>  b'' b'' b'' b'\r\n' b'ring\r\n' b'ata\r\n' b'ring\r\n' b'ata\r\n' b'ring\r\n' b'ata\r\n' b'ring\r\n' 

results ats0:

>>> ================================ restart ================================ >>>  b'' b'' b'' b'\r\n' b'ring\r\n' b'ats0\r\n' b'ring\r\n' b'ats0\r\n' b'ring\r\n' 

as see above, gsm modem regardless of @ command send it, continue ringing. what's wrong program?

note modem d-link dwm-156 , can send sms or make call using in python. in advance.

add end of each at command cr make valid at command