ZWave Speaker for Announcing Messages

  1. For now, Amazon does not allow Echo to do unprompted notifications. It may come as a future update.

  2. There are several approaches for announcing messages.
    A. Similar to the Sonos, the Fabriq speaker has DNLA capability to act as TTS for Smartthings

https://smile.amazon.com/FABRIQ-Portable-Bluetooth-Speaker-Amazon/dp/B01LYZAWRO/ref=cm_cr_arp_d_product_top?ie=UTF8

B. Use an Android device (5.1 OS) with LANnouncer software and BigTalker

C. Use a dedicated doorbell that can play MP3 sounds

There are more options but that should get you started.