What Is Nat And How Does It Affect Voip; What's The Difference Between A Static Ip Address And A Dynamic Ip Address; What Effect Does This Have On Voip; What Is A Sip Proxy And Registrar - Talkswitch 48-CA User Manual

What is NAT and how does it affect VoIP?

Network Address Translation (NAT) allows multiple devices to share the same external
IP address to access resources on the Internet. NAT is typically used to allow all the
devices in a subscriber's local area network to access the Internet through a router
with a single public IP address assigned by the Internet Service Provider.
If a VoIP device is sitting behind a NAT, the private IP address assigned to it is not
usable for communications with the entities outside the private network. The VoIP
device must substitute the private IP address information with the proper external IP
address/port in the mapping chosen by the underlying NAT to communicate with a
particular public peer address/port. TalkSwitch can automatically check for the
current public IP address and substitute the private IP address with the public address
so that VoIP traffic is properly routed through the NAT.
What's the difference between a Static IP Address and a Dynamic IP
Address? What effect does this have on VoIP?
A Static IP Address is an address that is permanently assigned to a device. Typically, a
Static IP Address has to be assigned by the network administrator or Internet Service
Provider (ISP).
A Dynamic IP Address is an address that is temporarily assigned to devices by a DHCP
or PPP server that maintains and assigns a pool of IP addresses.
When deploying VoIP devices, it's best to have a Static Public IP Address as this
prevents destinations from becoming unreachable for periods of time when the IP
address changes. But since this can be an expensive option, TalkSwitch 48-CVA
supports the ability to handle Dynamic Public IP addresses for the Internet
connection. TalkSwitch can automatically check for the current public IP address and
substitute the private IP address with the public address so that VoIP traffic is properly
routed through the NAT.

What is a SIP Proxy and Registrar?

SIP's basic architecture is client/server in nature. The main entities in the SIP server
are the Proxy, Redirect Server and the Registrar.
TalkSwitch 48-CVA has the SIP Server fully integrated for easy deployment and
maintenance of your VoIP network. If you are deploying a multi-site configuration
which can comprise of TalkSwitch 48-CVA units, certified 3rd party gateways and
certified 3rd party SIP phones, then one TalkSwitch 48-CVA can act as the SIP Proxy
and Registrar. The other SIP end-points will register with this TalkSwitch 48-CVA and
all calls will be negotiated through this TalkSwitch 48-CVA.
When you first set up your VoIP device (TalkSwitch 48-CVA, gateway or phone), it will
register itself with the TalkSwitch 48-CVA that is configured as the SIP Server so that
calls can be directed to your location.
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