[Asterisk-Users] How to connect to Asterisk to IPTEL.ORG

[Alex Piqueras]

Hi.
I have connected my Asterisk (inside my NAT) to IPTEL.org.
I can call others users of iptel, but anyone can call me. They listen a busy 
tone

Someone can help me???

my sip.conf:
register => prueba22:password at iptel.org/phone2

[iptel]
type=friend
host=iptel.org
port=5060
fromdomain=iptel.org
fromuser=prueba22
username=prueba22
secret=pass
nat=yes
canreinvite=no
context=prueba


My Asteriks shows the following information:

*CLI> sip show registry
Host                            Username       Refresh State
iptel.org:5060               prueba22           105 Registered

And someone can tell my others free VoIP SIP providers to try???

PD: Si hay alguien que hable español me haría un gran favor si me escribiera 
directamente a mi mail a_piqueras at hotmail.com muchas gracias