Incoming call-limit can be controlled in FreeSWITCH from user directory for example:

<document type=”freeswitch/xml”>
  <section name=”directory”>
    <domain name=”192.168.0.2″>
      <user id=”some_user”>
        <params>
          <param name=”password” value=”some_password”/>
        </params>
        <variables>
                       <variable name=”accountcode” value=”315″/>
                       <variable name=”user_context” value=”default”/>
                       <variable name=”vm_extension” value=”315″/>
                       <variable name=”max_calls” value=”1″/>
          </variables>
      </user>
    </domain>
  </section>
</document>