Hello Eranga ,
Any paltform’s life / support depend’s on it’s users.
You need to decide based on the resources you have and the time constrait’s.
If you have good develeoper’s and budgets in place go for Erlang.
If you have limited resources depend on linux – a good and well supported environment.
Can you explain the scalability problems you have ?
Are you working for voice communication only or data communication ?
No of users ( simultaneous ) and data rates you are planning will give a good in sight of the system.
Are you in Australia ?