I have seen this object referred to in a few different posts but I am not able to find it in version 7 of the wsdl i used for my Java project.
 
Does anyone know with what version this object became available? I have been able to apply the getPhone object to return the line array and then using Iteration to set the device specific line changes to display and  label but I have not be successul in applying the changes via updatePhone.  
 
Disclaimer:  I am newer to Java and the AXL API but have been fairly successful up to this point.  

From an XML perspective, getPhone provides a <result> that has <device>/<lines> list:
          ...
         <return>
            <device ctiid="41" uuid="{0BD09152-AEAE-4173-4ABB-B7310F47DD36}">
               <name>SEP00215ACAAAAA</name>
               <description>SEP00215ACAAAAA</description>
               <product>Cisco 6941</product>
               ...
              <associatedPC/>
               <lines>
                  <line index="1" uuid="{3EABB7BB-7A42-64E6-3C50-622EF0A9C3F1}">
                     <label>(114)</label>
                     <asciiLabel>(114)</asciiLabel>
                     <display>(114)</display>
                     ...
You can then use this structure in <updatePhone>/<lines>:
   <ns:updatePhone sequence="1">
         <name>SEP00215ACAAAAA</name>
         <lines>
            <line index="1" uuid="{3EABB7BB-7A42-64E6-3C50-622EF0A9C3F1}">
               <label>newlabel</label>
               <asciiLabel>(114)</asciiLabel>
               <display>(114)</display>
                ...