With base address

<service name="WCFService.Service" behaviorConfiguration="behaviorConfig">
<host>
  <baseAddresses>
    <add baseAddress="net.tcp://localhost:1645/ChatServer/"/>
  </baseAddresses>
  </host>
 <endpoint address="tcp"
                  binding="netTcpBinding"
                  bindingConfiguration="tcpBinding"
                  contract="ChatService.IChat"/>

 <endpoint address="mex"
                  binding="mexTcpBinding"
                  contract="IMetadataExchange"/>

 </service>

Without base address

<service name="WCFService.Service" behaviorConfiguration="behaviorConfig">
 <endpoint address="net.tcp://localhost:1645/ChatServer/tcp"
                  binding="netTcpBinding"
                  bindingConfiguration="tcpBinding"
                  contract="ChatService.IChat"/>

 <endpoint address="net.tcp://localhost:1645/ChatServer/mex"
                  binding="mexTcpBinding"
                  contract="IMetadataExchange"/>

 </service>