2Factor Transactional API allows you to pull delivery reports offline using below mentioned endpoint.

Endpoint:

• http://2factor.in/API/V1/{api_key}/ADDON_SERVICES/RPT/TSMS/{session_id}
  
  
• Request Details:
  Type of request: GET
• Parameters:
  api_key: 2Factor account API Key
  session_id: Session id generated on Send SMS API Request
  
  
• Output Format: XML
  
  

Sample output:
<smsLog>
    <logStatus>Valid</logStatus>
    <sms>
        <smsMeta>
            <smsFrom>DIALTV</smsFrom>
            <smsTo>918431345565</smsTo>
            <smsDate>2015-11-30</smsDate>
            <creditsCharged>1</creditsCharged>
        </smsMeta>
        <smsStatus>
            <sentAt>2015-11-30 19:54:59</sentAt>
            <deliveredAt>2015-11-30 19:55:02</deliveredAt>
            <statusDesc>DELIVERED</statusDesc>
            <statusId>5</statusId>
            <statusGroupId>3</statusGroupId>
        </smsStatus>
        <smsError>
            <errorId>0</errorId>
            <errorGroupId>0</errorGroupId>
            <isPermanent>false</isPermanent>
        </smsError>
    </sms>
    <sms>
        <smsMeta>
            <smsFrom>DIALTV</smsFrom>
            <smsTo>918431345566</smsTo>
            <smsDate>2015-11-30</smsDate>
            <creditsCharged>1</creditsCharged>
        </smsMeta>
        <smsStatus>
            <sentAt>2015-11-30 19:54:59</sentAt>
            <deliveredAt>2015-11-30 19:55:03</deliveredAt>
            <statusDesc>DELIVERED</statusDesc>
            <statusId>5</statusId>
            <statusGroupId>3</statusGroupId>
        </smsStatus>
        <smsError>
            <errorId>0</errorId>
            <errorGroupId>0</errorGroupId>
            <isPermanent>false</isPermanent>
        </smsError>
    </sms>
</smsLog>

For more details on Status and Error Group Ids and corresponding descriptions,
please visit Here