iotum talk-now is not just an other blackberry messenger, no this software is a so called New Presence application, be notified when somebody wants to speak to you or share your availability with other blackberry users.

1. Share your person-to-person availability to let people know when to reach you. This status will be shared when a user adds you to his Talk-Now list or when you notify a contact to return your call. Your availability to take a call from a specific contact is defined by iotum based on:
   1. What you are doing (calendar, presence on BlackBerry)
   2. Your preferences: set up when you are available or not for a call; apply different priorities and preferences to different contacts or groups of contacts.
   3. Who is requesting the information
2. Show at a glance the personalized availability of your preferred contacts. Add contacts to the to-call list and see their availability for a call.
3. Notify you when a contact becomes available.

iotum is available for Blackberry OS 4.1 or higher, you can download it here