Switches are a great and necessary thing for a network, but for VOIP they require special consideration.

Unmanaged switches (or dumb switches) are the easiest to use with VOIP systems, as they require no special settings or configuration.
We recommend that you avoid 4 or 5 port switches in favor of 8+ ports, as the 4 and 5 port switches are generally low quality and less reliable.
Most unmanaged 8+ port switches can be had for $20-30.
Please note - Managed switches that are not managed are not the same thing as an unmanaged switch.

Managed switches require proper configuration to work with VOIP systems.
Please note - an unconfigured managed switch is not the same as an unmanaged switch.
If using a managed switch, you will need an IT person.