There are a several timeout setting not only the sentTimeOut, always remember that just because you don't see a setting doesn't mean it doesn't exist.
There are several settings and if you don't see it, it will use its default value.
Note the various Timeout settings here:
<binding name="WSHttpBinding_ITimeOutDemoService" closeTimeout="00:10:00"
openTimeout="00:10:00" receiveTimeout="00:10:00" sendTimeout="00:10:00" ........
<reliableSession ordered="true" inactivityTimeout="00:10:00"
There is also the executionTimeout in the web.config which is set under configuration - system.web - httpRuntime executionTimeout as shown below.
The default for this is 110 seconds. When you have slow service operations which could causes timeouts to occur the request will be aborted and you will find an entry in the ASP.NET EventLog that informs you that the request has timed out.
Note that 600 is 10 minutes.
Then remember that if IIS is hosting the WCF Service there are timeout settings which need to be managed there as well.
This is certainly not all there is to know about TimeOut settings but I hope this points you in the right direction.
Good luck Emily