'Access the sip
:returns: twilio.rest.api.v2010.account.sip.SipList
:rtype: twilio.rest.api.v2010.account.sip.SipList'

@property
def sip(self):

    if (self._sip is None):
        self._sip = SipList(self._version, account_sid=self._solution['sid'])
    return self._sip
