Visual voicemail app maker YouMail said its latest update to the BlackBerry version of its app will be its last for RIM's OS.

In an official blog post, the company said a new version announced last week is “a bittersweet release,” because it is suspending further work for this platform – for the time being at least.

The decision was taken due to the BlackBerry audience for the app shrinking steadily over the past 12 months as consumers have moved on to the iPhone or Android.

YouMail has seen the number of BlackBerry users per day plummet, while numbers for for iOS and Android have soared. Indeed, the company is often getting fewer users on BlackBerry devices than on Windows Phone, despite not having an official app for the Microsoft platform.

YouMail said it was a tough decision as BlackBerry was the first platform to embrace its technology and was the source of its first one million registered users.

The blog post added that YouMail is rooting for RIM’s next-generation BlackBerry 10 OS to take off, in which case it will resume developing for the platform if it can attract sufficient user numbers.

The latest version of YouMail for the BlackBerry platform has the option for users to reject callers by giving them a number out of services message and not allowing them to leave a voicemail.  It also features a faster user interface, greater stability and does away with ads despite remaining free to use.