Go for one initial email and phone number. Let the user add more only if really needed.

app/controllers/contacts_controller.rb

@@ -8,10 +8,8 @@ class ContactsController < ApplicationController
 
   def new
     @contact = Contact.new
-    3.times do
-      email = @contact.emails.build
-      phone = @contact.phones.build
-    end
+    email = @contact.emails.build
+    phone = @contact.phones.build
 
     # list of valid months and days
     @months = Array.new