However, I prefer to ensure that the DNS servers are manually set, as well as automatically retrieved via DHCP, to ensure reliability, redundancy, and backup.

For the purposes of this tutorial, I will be using Call Centric as the Vo IP service to be configured into EXT1 of the SPA504G.

I have been using Call Centric myself for years now and know that they are an excellent and reliable BYOD Vo IP service.

DNS servers lookup the IP address of an Internet resource based on domain name to IP address cross referencing.

Typically, we configure a Vo IP proxy based on its domain name (i.e. DNS servers will redirect your Internet traffic to the appropriate IP address of the Vo IP proxy.

The same goes for the NTP (Network Time Protocol) time servers.

Your ATA or IP-Phone uses NTP time servers for tagging and maintaining the correct device time.

NTP time servers are generally listed by domain names.

The DNS servers will direct the NTP requests to the appropriate NTP time server IP addresses.

By default, the SPA504G should retrieve the DNS server info from your Internet Modem DHCP server.

of the Default settings will work right out of the box, as is.

The point of this tutorial is to guide you through the most basic and essential setting changes required to get started making calls. This tutorial is geared to the new and unfamiliar user who has just acquired their first Cisco SPA504G IP-Phone.

While this tutorial is not comprehensive, it does get you connected to Call Centric and ready to make calls.

Before configuring the SPA504G with a BYOD Vo IP service provider, such as Call Centric, there are a few points that should be addressed first.