To check if a particular aliasCC is still valid, the card check api can be used. The only difference to a normal authorisation is the amount which has to be set to 0.

Using the Authorization API

curl -v -X POST https://api.sandbox.datatrans.com/upp/jsp/XML_authorize.jsp \
-H 'Content-Type: application/json' \
-H 'Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=' \
-d @- << EOF
<?xml version="1.0" encoding="UTF-8" ?>
<authorizationService version="6">
  <body merchantId="1000011011">
    <transaction refno="358838">
      <request>
        <amount>0</amount>
        <currency>CHF</currency>
        <reqtype>CAA</reqtype>
        <aliasCC>70323122544331174</aliasCC>
        <expm>12</expm>
        <expy>21</expy>
        <sign>30916165706580013</sign>
      </request>
    </transaction>
  </body>
</authorizationService>
EOF

<?xml version='1.0' encoding='UTF-8'?>
<authorizationService version='6'>
  <body merchantId='1000011011' status='accepted'>
    <transaction refno='358838' trxStatus='response'>
      <request>
        <amount>0</amount>
        <currency>CHF</currency>
        <aliasCC>70323122544331174</aliasCC>
        <expm>12</expm>
        <expy>21</expy>
        <sign>30916165706580013</sign>
        <reqtype>NOA</reqtype>
      </request>
      <response>
        <responseCode>01</responseCode>
        <responseMessage>Authorized</responseMessage>
        <uppTransactionId>181005110358506719</uppTransactionId>
        <authorizationCode>358536720</authorizationCode>
        <acqAuthorizationCode>110358</acqAuthorizationCode>
        <maskedCC>375811xxxxx1115</maskedCC>
      </response>
    </transaction>
  </body>
</authorizationService>