[AsteriskBrasil] Erro ao tentar conectar SIP Phone

[Bruno Fantoni]

Olá Pessoal,

sou novo por aqui e estou terminando minha primeira compilação do Asterisk.
Depois da instalação, estou tentando conectar 
utilizando um softphone e obtenho o seguinte erro :

Apr 19 15:04:15 WARNING[26403] res_musiconhold.c: 
Unable to open pseudo channel for timing...  Sound may be choppy.
Apr 19 15:04:15 WARNING[26403] chan_iax2.c: 
Unable to open IAX timing interface: No such file or directory
Apr 19 15:04:17 NOTICE[26416] chan_iax2.c: No 
registration for peer 'fantoni' (from 200.150.13.250)
Apr 19 15:04:35 NOTICE[26421] chan_sip.c:    -- 
Registration for 'fantoni em 200.150.13.250' timed out, trying again (Attempt #1)
Apr 19 15:04:55 NOTICE[26421] chan_sip.c:    -- 
Registration for 'fantoni em 200.150.13.250' timed out, trying again (Attempt #2)

Tenho as seguintes configurações no /etc/sip.conf :

[fantoni]
type=friend
secret=fantoni
qualify=200                    ; Qualify peer is no more than 200ms away
nat=yes                        ; This phone may be natted
                                 ; Send SIP and 
RTP to the IP address that packet is
                                 ; received from 
instead of trusting SIP headers
host=dynamic                   ; This device registers with us
canreinvite=no                 ; Asterisk by default tries to redirect the
                                 ; RTP media stream (audio) to go directly from
                                 ; the caller to 
the callee.  Some devices do not
                                 ; support this (especially if one of them is
                                 ; behind a NAT).
;defaultip=192.168.0.4          ; IP address to use until registration
username=fantoni                 ; Username to 
use when calling this device before registration
	                                ; Normally you 
do NOT need to set this parameter
setvar=CUSTID=5678             ; Channel variable 
to be set for all calls from this device
regexten=1234
context=sip

Alguém teria uma luz ?

Obrigado,

Bruno Fantoni