References to “8500” are examples based on a default configuration. For these examples to work, it is necessary to manually create an extension 8500, then change its type to be “Voicemail Pickup” in the Extensions Edit screen. On a multi-company system, this extension should be owned by the “Default company”
On more modern PABX versions, ‘**40’ is permanently set to try and pick up voicemail on a handset device.