WARNING[7125]: app_dial.c:1310 dial_exec_full: Unable to create channel of type 'SIP' (cause 20 - Unknown)
[Mar 8 11:48:32] == Everyone is busy/congested at this time (1:0/0/1)
[Mar 8 11:48:32] -- Executing [916267985848@default:3] Hangup("Local/916267985848@default-feff,2", "") in new stack
[Mar 8 11:48:32] == Spawn extension (default, 916267985848, 3) exited non-zero on 'Local/916267985848@default-feff,2'
[Mar 8 11:48:32] -- Executing [h@default:1] DeadAGI("Local/916267985848@default-feff,2", "agi://127.0.0.1:4577/call_log--HVcauses--PRI-----NODE-------") in new stack
[Mar 8 11:48:32] -- AGI Script
agi://127.0.0.1:4577/call_log completed, returning 0
[Mar 8 11:48:32] -- Executing [917075452561@default:2] Dial("Local/917075452561@default-aa87,2", "SIP/17075452561@APN||TtoR") in new stack
[Mar 8 11:48:32] WARNING[7128]: app_dial.c:1310 dial_exec_full: Unable to create channel of type 'SIP' (cause 20 - Unknown)
[Mar 8 11:48:32] == Everyone is busy/congested at this time (1:0/0/1)
[Mar 8 11:48:32] -- Executing [917075452561@default:3] Hangup("Local/917075452561@default-aa87,2", "") in new stack
[Mar 8 11:48:32] == Spawn extension (default, 917075452561, 3) exited non-zero on 'Local/917075452561@default-aa87,2'
[Mar 8 11:48:32] -- Executing [h@default:1] DeadAGI("Local/917075452561@default-aa87,2", "agi://127.0.0.1:4577/call_log--HVcauses--PRI-----NODE-------") in new stack
[Mar 8 11:48:32] == Parsing '/etc/asterisk/manager.conf': [Mar 8 11:48:32] Found
[Mar 8 11:48:32] == Manager 'sendcron' logged on from 127.0.0.1
[Mar 8 11:48:32] -- Executing [914062914969@default:1] AGI("Local/914062914969@default-0c47,2", "agi://127.0.0.1:4577/call_log") in new stack
[Mar 8 11:48:32] -- AGI Script
agi://127.0.0.1:4577/call_log completed, returning 0
[Mar 8 11:48:32] -- Executing [914062914969@default:2] Dial("Local/914062914969@default-0c47,2", "SIP/14062914969@APN||TtoR") in new stack
[Mar 8 11:48:32] WARNING[7133]: app_dial.c:1310 dial_exec_full: Unable to create channel of type 'SIP' (cause 20 - Unknown)
[Mar 8 11:48:32] == Everyone is busy/congested at this time (1:0/0/1)
[Mar 8 11:48:32] -- Executing [914062914969@default:3] Hangup("Local/914062914969@default-0c47,2", "") in new stack
[Mar 8 11:48:32] == Spawn extension (default, 914062914969, 3) exited non-zero on 'Local/914062914969@default-0c47,2'
[Mar 8 11:48:32] -- Executing [h@default:1] DeadAGI("Local/914062914969@default-0c47,2", "agi://127.0.0.1:4577/call_log--HVcauses--PRI-----NODE-------") in new stack
[Mar 8 11:48:32] == Parsing '/etc/asterisk/manager.conf': [Mar 8 11:48:32] Found
[Mar 8 11:48:32] == Manager 'sendcron' logged on from 127.0.0.1
[Mar 8 11:48:32] -- Executing [919095873108@default:1] AGI("Local/919095873108@default-83a5,2", "agi://127.0.0.1:4577/call_log") in new stack
[Mar 8 11:48:32] -- AGI Script
agi://127.0.0.1:4577/call_log completed, returning 0
[Mar 8 11:48:32] -- Executing [919095873108@default:2] Dial("Local/919095873108@default-83a5,2", "SIP/19095873108@APN||TtoR") in new stack
[Mar 8 11:48:32] WARNING[7137]: app_dial.c:1310 dial_exec_full: Unable to create channel of type 'SIP' (cause 20 - Unknown)
[Mar 8 11:48:32] == Everyone is busy/congested at this time (1:0/0/1)
[Mar 8 11:48:32] -- Executing [919095873108@default:3] Hangup("Local/919095873108@default-83a5,2", "") in new stack
[Mar 8 11:48:32] == Spawn extension (default, 919095873108, 3) exited non-zero on 'Local/919095873108@default-83a5,2'
[Mar 8 11:48:32] -- Executing [h@default:1] DeadAGI("Local/919095873108@default-83a5,2", "agi://127.0.0.1:4577/call_log--HVcauses--PRI-----NODE-------") in new stack
help me for this error