[asterisk-users] register => 2345:password at sip_proxy/1234

[tjoen]

sip.conf.sample:
;register => 2345:password at sip_proxy/1234
;
;   Register 2345 at sip provider 'sip_proxy'.  Calls from this provider
;   connect to local extension 1234 in extensions.conf, default context,
;   unless you configure a [sip_proxy] section below, and configure a
;   context.

sip.conf:

[general]
context=default
allowoverlap=no
udpbindaddr=0.0.0.0
tcpenable=no
tcpbindaddr=0.0.0.0
srvlookup=yes
register => tjoen:mypasswd at sip_proxy/1234
qualify=yes
externip=myipnr
localnet=192.168.254.0/255.255.255.0
nat=yes

[sip_proxy]
type=peer
host=ekiga.net

extensions.conf:
[default]
include => demo
exten => 1234,1,Dial(SIP/2133)

Output of asterisk -vvv
...
REGISTER 11 headers, 0 lines
Reliably Transmitting (NAT) to 86.64.162.35:5060:
REGISTER sip:sip_proxy SIP/2.0
Via: SIP/2.0/UDP myipnr:5060;branch=z9hG4bK70f05590;rport
Max-Forwards: 70
From: <sip:tjoen at ekiga.net>;tag=as71be7ded
To: <sip:tjoen at ekiga.net>
Call-ID: 5a965c7e5d8a667b73cd18777f76704c at 127.0.0.1
CSeq: 102 REGISTER
User-Agent: Asterisk PBX 1.6.2.1
Expires: 120
Contact: <sip:1234 at myipnr>
Content-Length: 0
...
Retransmitting #1 (NAT) to 86.64.162.35:5060:
REGISTER sip:sip_proxy SIP/2.0
..

and:
[Mar 19 15:44:04] WARNING[2005]: chan_sip.c:11600 transmit_register:
Probably a DNS error for registration to tjoen at sip_proxy, trying
REGISTER again (after 20 seconds)

What am I doing wrong?