If you're an end user, you need to reach out to IT, and since IT doesn't know what to do, then IT should be the ones posting here providing information of what their setup looks like, call flow, products, versions, etc. Otherwise, they should open a support case with whoever is providing next level support to them a partner or Cisco TAC.
Your description doesn't provide enough information to tell you what needs to be changed or what to look at.
HTH
java
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