In my knowledge, there is no available plugin that can do this. This requires custom programming. This can only be done using custom WordPress plugin.
First of all, you would need a subscription form of some kind to get subscriber’s mobile number.
The plugin can then integrate with WordPress using one of WordPress hooks such as “save_post” and whenever a new post is published, send messages to all subscribed numbers by calling Nexmo REST API using any available library like “Nexmo-PHP-lib by Darren Whitlen”.
https://github.com/prawnsalad/Nexmo-PHP-lib
http://codex.wordpress.org/Plugin_API/Action_Reference/save_post