Changing various user URI's based on SIP addresses

Hi,

Is there a way using Powershell, that we can take part of a SIP address, filter users by it, then change only 'part' of their Lync URI address (but not the internal extensions, example not the ;ext=XXXXX).

Example.

Ken Smith, his SIP address is ken.smith@conso1.com
His Lync User URI is +441234111222;ext=55555

Kelly Smith, her SIP address is kelly.smith@conso1.com
Her Lync User URI is +441234111222;ext=55556

But we also have users with the similar:

Kevin Smith, his SIP address is kevin.smith@conso2.com
His Lync User URI is +441234111222;ext=55557

Therefore in the above example, we would want to look at our users that have the SIP Address = @conso1.com and would like to change their user URIs from +441234111222 to +441234222222.

Is this possible to change part of the user URI to +441234222222 yet keep their unique ';ext=XXXXX' at the end?

Thanks