If you are using an Aastra or Polycom phone and the dialing behavior of these devices has changed recently, you most likely need to re-download the configuration files into the phone.
Normal dialing behavior should be dialing 4-digits for an extension in your office and then the phone initiating the call automatically - without having to press the dial button or send button (depending on your model of IP Phone).
When this auto-dial behavior stops working, it's very likely that your phone has lost its internal Dial Plan which keeps a list of the types of digits it will accept before automatically initiating a call.
To re-download the configuration files for your phones, please do the following:
Explanation of what you've accomplished - When you set the device for an extension to voicemail-only, you are telling the system to remove the configuration file for the phone from the system. Then when you set the device back to the MAC address, you're telling the system to download the newly created configuration file from Fonality's Data Cluster where all configuration files are backed up via our Hybrid-Hosted technology. This newly-downloaded configuration file should contain the correct dial plan for the phone (the one that auto-dials the extension). Once you flash the phone, you're telling the phone to re-download it's configuration files, apply the correct dial string, and the phone's dialing behavior should return to normal as a result.