How to change sip address after changing email address for bulk users

Question

We are in the process of adding new primary email address as [email protected] for 500 users. 
current primary email address is [email protected] and 
currently all LYNC users has sip address as [email protected]
Now we need to change the LYNC SIP Address as their primary email address ( [email protected]). does any one has script to pull the users from CSV and change the SIP Address as their primary email address.
I got below script from internet , but this is not going to help me, as this script is to enable SIP Address and mark the sip address as same as the email address.
any help in this matter is greatly appreciated.
$users=Import-Csv .\users.csv
ForEach ($user in $users){
    Write-Host    $user.alias
    get-csaduser $user.alias | Enable-CsUser -RegistrarPool "PoolServer.domain.com" - SipAddressType EmailAddress
Srinivasa K

Answer 1

Raju, getting below error.
You cannot call a method on a null-valued expression.
At C:\Srini\lync.ps1:5 char:4
+    $newAddress=$oldAddress.Substring(0,$oldAddress.IndexOf("@"))+"@test.com"
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull
Set-CsUser : Cannot bind argument to parameter 'Identity' because it is null.
At C:\Srini\lync.ps1:6 char:25
+    Set-CsUser -Identity $User.Identity -SipAddress $newAddress
+                         ~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [Set-CsUser], ParameterBindingV
   alidationException
    + FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,M
   icrosoft.Rtc.Management.AD.Cmdlets.SetOcsUserCmdlet
You cannot call a method on a null-valued expression.
At C:\Srini\lync.ps1:5 char:4
+    $newAddress=$oldAddress.Substring(0,$oldAddress.IndexOf("@"))+"@test.com"
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull
Set-CsUser : Cannot bind argument to parameter 'Identity' because it is null.
At C:\Srini\lync.ps1:6 char:25
+    Set-CsUser -Identity $User.Identity -SipAddress $newAddress
+                         ~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [Set-CsUser], ParameterBindingV
   alidationException
    + FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,M
   icrosoft.Rtc.Management.AD.Cmdlets.SetOcsUserCmdlet
Srinivasa K