The actual task of upgrading your ShoreTel system from one software version to the other is "brilliantly simple".  The process, however, requires attention to the   detail!  Any software upgrade will challenge your "change management" process!  It is a complex process with many moving parts and it is up to you to understand what those parts are and how upgrading your software will effect those parts. Even a small ShoreTel deployment has many touch points beyond the upgrade of the server software.   How many servers do you have in your deployment?  Do you use CSTA?  Citrix? Vmware? Are you on a 32 bit platform?  Is it the right version to support the new Version of ShoreTel?  What hardware do you have in your deployment that might no longer be supported by the new ShoreTel software upgrade?  These are only a few of the more obvious questions you should be asking! Where do you get answers to these questions?  It is essential that your review the ShoreTel Release and Build notes prior to attempting an upgrade.  These notes are an invaluable source of  information that can provide needed detail on all key issues related to your upgrade.   ShoreTel also provides "tips and tricks" and with V13 there is a new compatibility tool available.   Compatibility guides, firmware lists, bug fixes as well as "known issues"  will be outlined in these documents.  Together with the system administration guide and planning  guide, these documents are absolutely essential for your review before attempting  an upgrade. Have you backed up your configuration?   There is no excuse for a system administration professional to attempt an upgrade without a backup of the system configuration, database, prompts and everything you need to restore a system from bare metal!   (See also http://www.blog.drvoip.com/backing-up-your-ipbx-call-center-what-is-your-plan ).   Do you have a written upgrade plan?  Team assignments?   "Hands and feet" available at each site?  Have you reduced the time needed to do this upgrade by previously downloading the required software?   This is a "resume creating event"!  After all how do you explain not having a fallback strategy? You will have alerted your User group to check voice mail messages before the upgrade and you will have provided them sufficient notice of the "maintenance window"  during which time the system will be unavailable.   Sometimes it is a good practice to call forward your main line to an alternative answering point during the upgrade!   Make sure the users know in advance about any new features or required  behavior they should expect post upgrade as nobody likes surprises!  We also recommend a "post cut" help desk be established and that the User group be made aware of the resouce when the system returns to service, post upgrade! We generally create a folder for our downloads and unpacking.  Get your software distributed out to each of your servers before hand, it will save you time!   The actual task list is very straight forward.   You will upgrade your HQ server first, during which time you will have an operating phone system without voice mail and automated attendant.    When this server comes back on line, upgrade your distributed servers next.   Some may argue that you should finish the HQ site first, but we recommend that you get all servers upgraded and communicating before upgrading the firmware in your ShoreGear switches and phones.  If you are going to find an upgrade issue, it will be with the servers, so lets get that behind us before addressing firmware! Next upgrade your ShoreGear switches. Logging into the ShorewareDirector administration portal will enable you to see that the switches are online, but not communicating with the server as they are in "yellow" alert as the result of a firmware mismatch.   Just restart them, the firmware will automatically be downloaded and installed.  Depending on the number of switches, don't restart them all at once!  Switches across the WAN are the most vulnerable, as any break in communication during the firmware download will cause your switches to become stupid!  You will need an appropriate serial cable to recovers, so that needs to be on your "required tools" list prior to upgrade. As your switches come alive with a Green indication and the correct firmware, start to reset your phones.  Your phones register with a specific Shoregear switch, so make sure that switch has completed its upgrade before restarting your phones.  When restarted they will automatically download and install new firmware.   You can restart the phones from inside ShorewareDirector! If you have taken the time to adequately review your deployment using a "change management" methodology, created the necessary backups, prepared in advance with a written upgrade plan including team assignments, you should have no trouble!    The old Carpenters adage rings true: measure twice and cut once! http://youtu.be/QaEn4w5hG4I