1) phonenum 28251000 removes the voice mail feature, so the system send delete VM API to CUPI. This step is ok without problem.
 
request: DELETE /vmrest/users/d842a51c-8b46-4187-a3da-4df6fe8abd2b
response -> statusCode:204, result:
 
2) Later on, we want to add the VM feature again to this phonenum. The problem is that the CUPI import list API cannot find the phonenum (there is no alias showing 28251000 as below). In normal case, it should show the record <ImportUser....> with alias "28251000" (just like the newly added on 80000002). 
 
request: GET /vmrest/import/users/ldap
response -> statusCode:200, result:<?xml version="1.0" encoding="UTF-8" standalone="yes"?><ImportUsers total="2"><ImportUser><alias>80000002</alias><firstName></firstName><lastName>80000002</lastName><pkid>4e8b928c-9835-4433-9b40-9976b6a45192</pkid></ImportUser><ImportUser><alias>90000002</alias><firstName></firstName><lastName>90000002</lastName><pkid>e9e8c758-b50b-4270-89f0-3fc015ad719b</pkid></ImportUser></ImportUsers>