# Step 1: Sender inputs proxy or account details

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Note: The process below is shown with demonstration screens in [*Sending Payments > Steps 7-9 Addressing, Proxy and Confirmation of Payee*](https://docs.nexusglobalpayments.org/payment-setup/steps-7-9-addressing-proxy-resolution-and-confirmation-of-payee).
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<figure><img src="https://260996932-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FdlTzGEXDmi664xppppmm%2Fuploads%2Fgit-blob-d10fcd0f61b9103c40e7e25fbb146b7da84282cb%2Fimage%20(17).png?alt=media" alt=""><figcaption><p>Flow diagram for setup of the addressing form in the Source PSP's app</p></figcaption></figure>

1. When the Sender selects the Destination Country for a payment in their PSP’s app, the Source PSP will call the `GET /countries/{countrycode}/addressTypes` API operation, specifying the country code. Nexus will respond with a full list of address types for that country, including any proxy types, Account Identification formats and/or IBAN. (See [*Address Types*](https://docs.nexusglobalpayments.org/addressing-and-proxy-resolution/address-types-and-inputs/address-types) for details.)
2. The Source PSP will show the Sender a form allowing them to select one of the possible address types, according to the details they were given by the Recipient.
3. The Sender selects an address type (eg the “Mobile” option on the form; in the case of a payment to Singapore, this would select the address type with the ID “*SGMBNO”*).
4. The Source PSP will call the `GET /addressTypes/{addressTypeId}/inputs` API operation to retrieve the input fields that are required for this address type.

{% hint style="info" %}
The Source PSP could retrieve the address inputs for all address types in a single API call by using\
`GET /countries/{countryCode}/addressTypesAndInputs/`\
\
instead of\
\
`GET /countries/{countryCode}/addressTypes/`
{% endhint %}

5. The Source PSP’s app will use the address inputs to generate the app form to enter the address details
6. The Sender will enter the details that they were given by the Recipient (eg “+6580001234”).
7. The Source PSP’s app must validate that the address details entered by the Sender are in the correct format. These validation rules will be provided as regular expressions (regex) in the address inputs information provided by Nexus. This allows the PSP to validate the format of the data in-app, prior to any communication with Nexus or the proxy scheme.
8. If the Sender entered **proxy details**, the Source PSP will prepare an ISO 20022 [`acmt.023`](https://docs.nexusglobalpayments.org/messaging-and-translation/message-acmt.023-identification-verification-request) message, following the **usage guidelines for** **proxy resolution.** The Source PSP will send the `acmt.023` (or equivalent API request) to Nexus.
   1. **See** [**Step 2**](https://docs.nexusglobalpayments.org/addressing-and-proxy-resolution/proxy-and-account-resolution-process/step-2-proxy-resolution-messaging-sequence) for further steps on proxy resolution.
9. If the Sender entered account details, the Source PSP will prepare an **ISO 20022** [**acmt.023**](https://docs.nexusglobalpayments.org/messaging-and-translation/message-acmt.023-identification-verification-request) message, following the **usage guidelines for** **account resolution.** The Source PSP will send the `acmt.023` (or equivalent API request) to Nexus.
   1. **See** [**Step 3**](https://docs.nexusglobalpayments.org/addressing-and-proxy-resolution/proxy-and-account-resolution-process/step-3-account-resolution-messaging-sequence) for further steps on account resolution.