Hi, Gsm got worked, two way signaling work. But now answer after answering the call. 2012-05-16 21:28:26.009824 [ERR] gsmopen_protocol.cpp:1853 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 1853 ][ ][-1,24,28] Error RE-sending (A): 10 -1 (Bad file descriptor) 2012-05-16 21:28:26.009824 [ERR] gsmopen_protocol.cpp:1859 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 1859 ][ ][-1,24,28] wrote -1 bytes!!! Nenormalno! Marking this gsmopen_serial_device /dev/ttyUSB3 as dead, andif it is owned by a channel, hanging up. Maybe the phone is stuck, switched off, power down or battery exhausted 2012-05-16 21:28:26.009824 [ERR] gsmopen_protocol.cpp:1862 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 1862 ][ ][-1,24,28] gsmopen_serial_monitor failed, declaring /dev/ttyUSB3 dead 2012-05-16 21:28:26.009824 [ERR] mod_gsmopen.cpp:2883 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 2883 ][ ][-1,24,28] ALARM on interface : 2012-05-16 21:28:27.009857 [ERR] gsmopen_protocol.cpp:2131 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 2131 ][ ][-1,24,28] Error sending data... (Bad file descriptor) 2012-05-16 21:28:27.009857 [ERR] gsmopen_protocol.cpp:2136 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 2136 ][ ][-1,24,28] wrote -1 bytes!!! Nenormalno! Marking this gsmopen_serial_device /dev/ttyUSB3 as dead, andif it is owned by a channel, hanging up. Maybe the phone is stuck, switched off, power down or battery exhausted 2012-05-16 21:28:27.009857 [ERR] gsmopen_protocol.cpp:2139 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 2139 ][ ][-1,24,28] gsmopen_serial_monitor failed, declaring /dev/ttyUSB3 dead 2012-05-16 21:28:27.009857 [ERR] mod_gsmopen.cpp:2883 rev 44fd0de|44fd0de[(nil)|37 ][ERRORA 2883 ][ ][-1,24,28] ALARM on interface : Thanks, Bala