If, for any reason, you need to change the maximum time (in seconds) that each call can last, you need to change value for option named Absolute Timeout (sec).
On single tenant edition, such as Contact Center or Business edition, Absolute Timeout option is available on the following location: Settings ---> Servers ---> General Settings
When it comes to a Multi Tenant edition, you may choose to change the maximum call length for entire system (for all tenants) or for specific tenant only.
In order to change maximum duration of the call for entire system, you need to log into system as an Administrator and navigate to the following location: Master Tenant ---> Settings ---> Tenants.
From this location, edit Master tenant and change the default value of the option Absolute Timeout (sec) from 14400 to something that fit your needs better.
If you want to change maximum duration of the call for a specific tenant only, then edit tenant in question from the Master Tenant ---> Settings ---> Tenants location and change the value: