Last week I had a client report that two users (out of around 300) were experiencing issues when calling into Exchange Unified Messaging. Although the Australian (en-AU) Language pack had been deployed, these users would still hear the US (en-US) language prompts. As the issue was specific to only two users, I had a look at their AD attributes, see if anything was different from other users. One value stood out as irregular:
These users had en-GB configured for the msExchUserCulture attribute. As only the default en-US and en-AU language packs were deployed, Unified Messaging was falling back to defaults when the region was incorrectly configured. One explanation as to why this was the case could be a user signing into Outlook Web App for the first time, and selecting the wrong region (thanks Dan).
Manually updating the value to en-AU resolved the issue without the need to disable/enable Unified Messaging for the user:
Small issue, simple fix, but interesting none the less.