The phase names are defined in languages/custom_en.php. 
We wanted to give you the option to define a number of phase sets with your own names and in any language you want. 

What you need to do is open customvales.php. Then there are two steps you need to perform to add a new phase set. 

Step 1. The bellow line is to define the names of the phases sets. You can have as many as you like. 
"sets" => array(1 => "Website", 2 => "CD"), 

So for example if you were to add a phase set called "Network Migration" the line would now look like: 

"sets" => array(1 => "Website", 2 => "CD", 3 => "Network Migration"), 

Step 2. Now you have to enter the actual names of the phases within a phase set. So to use the above example of adding a new phase set called Network Migration, you would add: 

"3" => array(0 => "Phase1", 1 => "Phase2", 2 => "Phase3"), 

The number 3 at the begining of the line relates to the number you have assigned to the name "Network Migration" in Step 1. 

So now the entire phase set array in customvalues.php would look like: 

$phaseArraySets = array( 
#Define the names of your phase sets 
"sets" => array(1 => "Website", 2 => "CD”, 3 => “Network Migration"), 
#List the indervitual items within each phase set. 
#Website Set 
"1" => array(0 => "Planning", 1 => "Design", 2 => "Production", 3 => "Testing", 4 => "Sign-off"), 
#CD Set 
"2" => array(0 => "Planning", 1 => "Design", 2 => "Production", 3 => "Testing"), 
#Network Migration Set 
"3" => array(0 => "Phase1", 1 => "Phase2", 2 => "Phase3") 
);