Mastering Office 365 Administration

Know whether you need a manual port 

The automated port request form is great if you're just moving a few desk phones from another provider to your Skype for Business accounts. However, it's not suitable for most other purposes, a fact that we find ironic because this is probably the least common scenario for businesses looking to port existing phone numbers. 

Microsoft says:

Let us help you by opening a service request if you need to do one or more of these:

• Transfer more than 999 user phone numbers
• Transfer service numbers such as for conference bridges, auto attendants, and call queues
• Transfer toll-free numbers in the U.S.
• Transfer any numbers in the U.K., Ireland, France, Spain, and the Netherlands
• If porting numbers isn't your thing ...