Some setup you must do manually if you haven’t yet(in config/initializers/devise.rb):

You need field in model for confirm phone(must be boolean).
config.phone_confirmation_field = :phone_confirm

Field in the model which returns the correct answer
config.sms_answer_field = :sms_answer

Field in model which phone number
config.phone_field = :phone

Path after successful confirmation
config.successful_path = '/'

SMS provider module(have default for STREAM-TELECOM) you can define own
   Provider module should be a method :send_sms
config.sms_provider = DeviseSmsVerifiable::Provider

Send sms silent for test
config.provider_silent = true

SMS provider login
config.provider_login = :provider_login

SMS provider password
config.provider_password :provider_password

SMS provider from
config.provider_from :provider_from