sip.conf

[general]
context=default                 ; Default context for incoming calls
;allowguest=no                  ; Allow or reject guest calls (default is yes)
allowoverlap=no                 ; Disable overlap dialing support. (Default is yes)
;allowtransfer=no               ; Disable all transfers (unless enabled in peers or users)
                                ; Default is enabled
realm=somehost.dyndns.org              ; Realm for digest authentication
                                ; defaults to "asterisk". If you set a system name in
                                ; asterisk.conf, it defaults to that system name
                                ; Realms MUST be globally unique according to RFC 3261
                                ; Set this to your host name or domain name
bindport=5060                   ; UDP Port to bind to (SIP standard port is 5060)
                                ; bindport is the local UDP port that Asterisk will listen on
bindaddr=0.0.0.0                ; IP address to bind to (0.0.0.0 binds to all)
srvlookup=yes


;----------------------------------------- NAT SUPPORT ------------------------
; The externip, externhost and localnet settings are used if you use Asterisk
; behind a NAT device to communicate with services on the outside.

externip = 11.11.11.11         ; Address that we're going to put in outbound SIP
                                ; messages if we're behind a NAT

                                ; The externip and localnet is used
                                ; when registering and communicating with other proxies
                                ; that we're registered with
;externhost=foo.dyndns.net      ; Alternatively you can specify an
                                ; external host, and Asterisk will
                                ; perform DNS queries periodically.  Not
                                ; recommended for production
                                ; environments!  Use externip instead
;externrefresh=10               ; How often to refresh externhost if
                                ; used
                                ; You may add multiple local networks.  A reasonable
                                ; set of defaults are:
localnet=192.168.10.0/255.255.255.0; All RFC 1918 addresses are local networks
;localnet=10.0.0.0/255.0.0.0    ; Also RFC1918
;localnet=172.16.0.0/12         ; Another RFC1918 with CIDR notation
;localnet=169.254.0.0/255.255.0.0 ;Zero conf local network

; The nat= setting is used when Asterisk is on a public IP, communicating with
; devices hidden behind a NAT device (broadband router).  If you have one-way
; audio problems, you usually have problems with your NAT configuration or your
; firewall's support of SIP+RTP ports.  You configure Asterisk choice of RTP
; ports for incoming audio in rtp.conf
;
nat=yes                         ; Global NAT settings  (Affects all peers and users)
                                ; yes = Always ignore info and assume NAT
                                ; no = Use NAT mode only according to RFC3581 (;rport)
                                ; never = Never attempt NAT mode or RFC3581 support
                                ; route = Assume NAT, don't send rport
                                ; (work around more UNIDEN bugs)

[4202]
type=friend
host=dynamic
username=4202
secret=somesecret
nat=yes
context=local-sip
canreinvite=no