Warning[2966] Retransmission timeout reached on transmission

Hi, I’m with problem with my asterisk 11

-- SIP/3020-0000001e answered SIP/3028-0000001d
[May  5 12:47:46] WARNING[2966]: chan_sip.c:4024 retrans_pkt: Retransmission timeout reached on transmission ajVID0ifnev3q6oXclDkyA.. for seqno 2 (Critical Response) -- See https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions
Packet timed out after 6400ms with no response
[May  5 12:47:46] WARNING[2966]: chan_sip.c:4053 retrans_pkt: Hanging up call ajVID0ifnev3q6oXclDkyA.. - no reply to our critical packet (see https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions).
== Spawn extension (ramais, 3020, 1) exited non-zero on 'SIP/3028-0000001d'

I can make call but cannot talk and listen nothing.

How can I fix this?

Follow the link displayed warning and you will find some useful advices, to correct this issue.