View source for SIP configuration for voip phone

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[250] 
username=250
type=friend
host=dynamic
secret=<secret password>
context=twig
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iptables rules for asterisk - https://www.voip-info.org/asterisk-firewall-rules/
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# SIP on UDP port 5060. Other SIP servers may need TCP port 5060 as well
 iptables -A INPUT -p udp -m udp --dport 5060 -j ACCEPT

 # IAX2- the IAX protocol
 iptables -A INPUT -p udp -m udp --dport 4569 -j ACCEPT

 # IAX - most have switched to IAX v2, or ought to
 iptables -A INPUT -p udp -m udp --dport 5036 -j ACCEPT

 # RTP - the media stream
 # (related to the port range in /etc/asterisk/rtp.conf) 
 iptables -A INPUT -p udp -m udp --dport 10000:20000 -j ACCEPT
 

 # MGCP - if you use media gateway control protocol in your configuration
 iptables -A INPUT -p udp -m udp --dport 2727 -j ACCEPT
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