Receiving "NO CARRIER" error while tring to make a call using GSM modem in Python -

i want make call using gsm modem. wrote below program:

import time import serial  recipient = "+98xxxxxxxxxx"  phone = serial.serial("com10",  115200, timeout=5) try:     time.sleep(0.5)     phone.write(b'atz\r')     time.sleep(1)     phone.write(b'atd"'+recipient.encode() +b'"\r')     while(1):         print(phone.readline())     time.sleep(0.5) finally:     phone.close() 

but when run receive output:

>>> ================================ restart ================================ >>>  b'atz\r\r\n' b'ok\r\n' b'atdxxxxxxxxxx\r\r\n' b'no carrier\r\n' 

what "no carrier" error means?

note can send sms successfully.

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this program use send sms:

import time import serial  recipient = "+98xxxxxxxxxx" message = "test"  phone = serial.serial("com10",  115200, timeout=5)   try:     time.sleep(0.5)     phone.write(b'atz\r')     time.sleep(0.5)     phone.write(b'at+cmgf=1\r')     time.sleep(0.5)     phone.write(b'at+cmgs="' + recipient.encode() + b'"\r')     time.sleep(0.5)     phone.write(message.encode() + b"\r")     time.sleep(0.5)     phone.write(bytes([26]))     time.sleep(0.5) finally:     phone.close() 

i found origin of error :

the syntax atd+98xxxxxxxxxx; followed terminating string. forgotten put semicolon @ end after number.

so replace

phone.write(b'atd"'+recipient.encode() +b'"\r') 

with

phone.write(b'atd"'+recipient.encode() +b';"\r') 

and works fine.

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based on brackets in this documents, thought using ";" optional. seems wrong.