VoIP over Broadband

[sridharvaidyanathan]

I have 2 Locations A & B both connected to the Internet using a Broadband connection & with public IP & Broadband Router for each Location,with Cisco Call Manager in Location A & Static NAT on TCP port 2000. I have 2 IP phones at each location. For them to communicate over Broadband, what are the necessary ports that need to be open or NATed?

[Aaron Harrison]

The phones use a UDP port in the range 16384-32767 for the RTP stream - this port is negotiated as the call in set up via SCCP. Unless whatever is doing your NAT does proper inspection of the SCCP protocol you'll likely have problems...

If you can, consider setting up a site-to-site VPN with out NAT between the sites as this will simplify things...

Aaron

[sridharvaidyanathan]

Do you mean that my broadband router should have exclusive support for SCCP or do you mean that the solution will work only with Cisco Router.?

[roluce]

Neither.

Ummmm... this rabbit hole goes quite deep. Are you sure you want to jump in?

The more proper questions that you could ask would likely be.

1. What protocol/ports does a Cisco Call Manager use inbound?

2. What protocol/port (ranges) does a Cisco Call Manager use outbound?

3. What protocol/ports does a Cisco IP Phone use inbound?

4. What protocol/port (ranges) does a Cisco IP Phone use outbound?

You'll need all this information to set up the firewall rules/NAT for the installation that you're describing. I don't know this information right off the top of my head.

Rob

[sridharvaidyanathan]

The UDP & TCP ports used by Cisco Call Manager & the clients are present in the following URL:

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00801a62b9.shtml

I want to know that since the IP Phones selects ports at random (anywhere between 16384-32767) for making a RTP session with the other IP Phone. How can I NAT at this scenario?

[orlando]

If your broadband router is capable of VPN you can go that route.

At a remote location,I have a linksys befsx41 connected via vpn and an ip phone with a static ip.

and it works fine.

[megaco123]

You may also want to think about call control channel or call signalling stuff.

Port 1720 I think ;)