Snom VoIP Phone - Manual (Page 10)

Installation
10
A valid IP address appropriate to the network in which the phone is
being used can be provided.
Selecting the Netmask
Similarly, the user will be asked to provide a Netmask:
Selecting the IP Gateway
If a valid Netmask has been provided, the user will be asked for the IP
address of the IP gateway:
Selecting the DNS Server
The last item for this series of network-related configuration is the IP
address for the DNS server:
Selecting the Tone Scheme
The user will then be asked for the tone scheme to be used on the
phone: