Dialplan & Maximum retries exceeded on transmission

Hello

My dialplan:
exten => s,1,Background(custom/hello)
exten => 10,1,Playback(digits/10)
exten => 11,1,Playback(digits/11)
exten => 10,2,Dial(IAX2/005)
exten => t,1,Background(custom/hello)
exten => i,1,Background(custom/bad)

The problem is that when called i hear hello, i choose 10 extension and call internal number (IAX2/005) but then it hangs. The same when i call and do nothing
i hear hello and after timeout again i hear hello (partially) and then connection is broken. It seems in both cases like it was after some specified time.
In logs i receive:

– Playing ‘custom/hello’ (language ‘en’)
[Mar 19 11:34:10] WARNING[1680]: chan_sip.c:1881 retrans_pkt: Maximum retries exceeded on transmission 3F33C21E-D53C11DB-A5A5DCA3-A41DF0A8@217.11.128.50 for seqno 101 (Critical Response)
[Mar 19 11:34:10] WARNING[1680]: chan_sip.c:1898 retrans_pkt: Hanging up call 3F33C21E-D53C11DB-A5A5DCA3-A41DF0A8@217.11.128.50 - no reply to our critical packet.

What’s wrong ?

Thanx

Looks like Asterisk tried but couldn’t connect to your IAX end point (or trunk).