# How to enroll a disposable with an external OTP

To enroll a disposable with an external otp have to:

* specify **`otpType=EXTERNAL_OTP`** in the [`DisposableCertificate`](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/data-objects#disposablecertificate)object. If not specified the default otpType is SMS.


Then use these methods:

* [`checkData`](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/lean-checkdata/lean-checkdata-method)/[`checkDataWitheIDAssertion`](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/lean-checkdata/lean-checkdata-eid-assertion-method) (optional) : check the validity of the objects passed to the enroll methods
* [`getDisposableContract`](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/lean-documents/lean-getdisposablecontract-method)/[`getDisposableContractWitheIDAssertion`](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/lean-documents/lean-getdisposablecontractwitheidassertion-method) (optional)
* an [**enroll** method](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/lean-enroll) : enroll the certificate
* `signPKCS1WithSHA256` in the FRA service or use SWS: sign the document
* [`uploadDoc`](/products/leandisposable/enterprise-documentation/developer-documentation/api-references/lean-documents/lean-uploaddoc-method)  to upload the evidence of the otp or the authentication flow (for example PDS2 banking flow) (optional)


***To use EXTERNAL_OTP as OTP the LRA has*** ***to be authorized.***