What Is A Sip Server; What Is Dynamic Dns; What Is The Drawback Of Using Dynamic Dns - Talkswitch CT.TS005.003904 User Manual

When deploying VoIP devices, it's best to have a static public IP address. This prevents
destinations from becoming unreachable for periods of time when the IP address changes. But
since this can be an expensive option, TalkSwitch supports the ability to handle dynamic public
IP addresses for the Internet connection. TalkSwitch automatically checks for the current public
IP address and substitutes the private IP address with the public address, so that VoIP traffic is
properly routed through NAT.

What is a SIP server?

The basic IP architecture is client/server in nature. The main entities in the SIP server are the
proxy, redirect server and the registrar.
Every TalkSwitch unit has a fully integrated SIP server for easy deployment and maintenance of
your VoIP network. If you are deploying a multi-site configuration, one TalkSwitch unit will act
as the SIP server for the entire VoIP network. The other IP end-points will register with the SIP
server and all calls will be negotiated through the SIP server.
When you first set up your VoIP device (TalkSwitch unit, gateway or phone), it will register
itself with the SIP server so calls can be directed to your location.
When you initiate a VoIP call, your VoIP device will contact the SIP server in order to obtain the
contact information for the destination you are trying to reach. Once the contact information is
received, the call is established directly between your location and the destination. The SIP
server is no longer involved in the call.
If the location of the SIP server has a dynamic IP address, you have to use the dynamic DNS
since the location of the SIP server becomes unreachable as soon as the IP address changes.

What is dynamic DNS?

Dynamic DNS is a Domain Name Service used with dynamic IP addresses. DNS is used to allow
devices to find other devices on the Internet by domain name rather than by IP address.
Dynamic DNS allows you to use a Fully Qualified Domain Name (FQDN) to locate a device with a
dynamic IP address. The FQDN does not change. There are companies on the Internet who can
provide you with a domain name that will work even if your IP address changes. Such companies
are www.dyndns.org, hn.org or www.no-ip.com. Please consult with them how to use their
service. The basic idea is you will receive a domain name like myname.homeip.net, which will
continue to point to your IP address as it changes. This is important for the location of the SIP
server if the public IP address is dynamic. All other locations will point to the SIP server's
domain name instead of its IP address.

What is the drawback of using dynamic DNS?

If the IP address of the location of the SIP server changes, but the new IP address hasn't been
propagated, other devices will not be able to contact the SIP server in order to place VoIP calls.
When DNS records are updated, they have to be sent all over the world so everyone will be aware
of the changes. Basically, one DNS server connects to another and swaps information. In many
cases, the DNS servers are updated very quickly. Updates should not take longer than 15
minutes to propagate throughout the DNS system. It is possible propagation could take longer
due to unforeseen traffic but it shouldn't take much more than an hour at the most.
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