Starting DAHDI/1-1 at ,s,1 still failed so falling back to

please tell me how to resolve issue

i am useing asterisk with freepbx

-- Starting simple switch on 'DAHDI/1-1'

[Dec 8 18:08:39] NOTICE[3723]: chan_dahdi.c:8786 ss_thread: Got event 18 (Ring Begin)…
[Dec 8 18:08:39] NOTICE[3723]: chan_dahdi.c:8786 ss_thread: Got event 18 (Ring Begin)…
[Dec 8 18:08:41] NOTICE[3723]: chan_dahdi.c:8786 ss_thread: Got event 2 (Ring/Answered)…
[Dec 8 18:08:41] NOTICE[3723]: chan_dahdi.c:8786 ss_thread: Got event 2 (Ring/Answered)…
== Manager ‘admin’ logged on from 127.0.0.1
== Manager ‘admin’ logged off from 127.0.0.1
[Dec 8 18:08:42] NOTICE[3723]: chan_dahdi.c:8786 ss_thread: Got event 18 (Ring Begin)…
[Dec 8 18:08:42] NOTICE[3723]: chan_dahdi.c:8786 ss_thread: Got event 18 (Ring Begin)…
== Starting DAHDI/1-1 at ,s,1 failed so falling back to exten ‘s’
== Starting DAHDI/1-1 at ,s,1 still failed so falling back to context ‘default’
– Executing [s@default:1] Playback(“DAHDI/1-1”, “vm-goodbye”) in new stack
[Dec 8 18:08:42] WARNING[3723]: chan_dahdi.c:2685 dahdi_enable_ec: Unable to enable echo cancellation on channel 1 (No such device)
[Dec 8 18:08:42] WARNING[3723]: chan_dahdi.c:2685 dahdi_enable_ec: Unable to enable echo cancellation on channel 1 (No such device)
– <DAHDI/1-1> Playing ‘vm-goodbye.ulaw’ (language ‘en’)
– Executing [s@default:2] Macro(“DAHDI/1-1”, “hangupcall”) in new stack
– Executing [s@macro-hangupcall:1] GotoIf(“DAHDI/1-1”, “1?skiprg”) in new stack
– Goto (macro-hangupcall,s,4)
– Executing [s@macro-hangupcall:4] GotoIf(“DAHDI/1-1”, “1?skipblkvm”) in new stack
– Goto (macro-hangupcall,s,7)
– Executing [s@macro-hangupcall:7] GotoIf(“DAHDI/1-1”, “1?theend”) in new stack
– Goto (macro-hangupcall,s,9)
– Executing [s@macro-hangupcall:9] Hangup(“DAHDI/1-1”, “”) in new stack
== Spawn extension (macro-hangupcall, s, 9) exited non-zero on ‘DAHDI/1-1’ in macro ‘hangupcall’
== Spawn extension (default, s, 2) exited non-zero on ‘DAHDI/1-1’
– Hungup ‘DAHDI/1-1’