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No, If you use the Private IP address behind the Firewall as your registration IP, there is not routing capability. &nbsp;<br />
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Your Firewall and you IPBX need to be SIP / NAT aware, and I don't know the settings for your Checkpoint. &nbsp;<br />
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Sorry..
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No, If you use the Private IP address behind the Firewall as your registration IP, there is not routing capability.  

Your Firewall and you IPBX need to be SIP / NAT aware, and I don't know the settings for your Checkpoint.  

Sorry..

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Found my own solution as the firewall would not allowed the phones to register.
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Found my own solution as the firewall would not allowed the phones to register.

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When the SIP phone that resides behind the checkpoint firewall tries to register with the SIP Proxy on the internet, the checkpoint firewall will use the IP from the firewall as the registering IP for the phone. The registering IP needs to be the IP of the internal IP address of the phone or the SIP proxy will not know how to reach the phone to direct a call to it.
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When the SIP phone that resides behind the checkpoint firewall tries to register with the SIP Proxy on the internet, the checkpoint firewall will use the IP from the firewall as the registering IP for the phone. The registering IP needs to be the IP of the internal IP address of the phone or the SIP proxy will not know how to reach the phone to direct a call to it.

How to make a sip phone register properly behind a Checkpoint Firewall

Voice over IP (VoIP) is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. Other terms commonly associated with VoIP are IP telephony, Internet telephony, broadband telephony, and broadband phone service. The term specifically refers to the provisioning of communications services (voice, fax, SMS, voice-messaging) over the public Internet, rather than via the public switched telephone network (PSTN).  Examples of the VoIP protocols are H.323, Media Gateway Control Protocol (MGCP), Session Initiation Protocol (SIP), H.248 (also known as Media Gateway Control (Megaco)), Real-time Transport Protocol (RTP), Real-time Transport Control Protocol (RTCP), Secure Real-time Transport Protocol (SRTP), Session Description Protocol (SDP), and Inter-Asterisk eXchange (IAX).

Voice Over IP

Telecommunication occurs when the exchange of information between two or more entities (communication) includes the use of technology. Communication technology uses channels to transmit information (as electrical signals), either over a physical medium (such as signal cables), or in the form of electromagnetic waves. The word is often used in its plural form, telecommunications, because it involves many different technologies.

Telecommunications

IP telephony (Internet Protocol telephony) is a general term for the technologies that use the Internet Protocol's packet-switched connections to exchange voice, fax, and other forms of information that have traditionally been carried over the dedicated circuit-switched connections of the public switched telephone network (PSTN). Using the Internet, calls travel as packets of data on shared lines, avoiding the tolls of the PSTN. The challenge in IP telephony is to deliver the voice, fax, or video packets in a dependable flow to the user.