> For the complete documentation index, see [llms.txt](https://docs.iyzico.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.iyzico.com/en/products/paypos-app2app/paypos-app2app-integration/initialize-payment.md).

# Initialize Payment

This service checks whether the required configurations have been completed on the Paynet side and then returns the deeplink\_url required for the transaction, along with the encryption\_key used to decrypt the encrypted data returned to the customer’s mobile application. To send a request to this service, a mobile session token (session\_key) must be used.

## POST /v1/softpos/init\_sale\_transaction

> Start Sale – init\_sale\_transaction

```json
{"openapi":"3.0.3","info":{"title":"PayPOS (Paynet) API","version":"1.0.0"},"tags":[{"name":"SoftPOS"}],"servers":[{"url":"https://api.paynet.com.tr","description":"Production"},{"url":"https://pts-api.paynet.com.tr","description":"Sandbox"}],"paths":{"/v1/softpos/init_sale_transaction":{"post":{"summary":"Start Sale – init_sale_transaction","tags":["SoftPOS"],"parameters":[{"name":"Session-Key","in":"header","required":true,"description":"Mobile session key","schema":{"type":"string"}},{"$ref":"#/components/parameters/ContentTypeHeader"}],"requestBody":{"required":true,"content":{"application/json":{"schema":{"$ref":"#/components/schemas/InitSaleRequest"}}}},"responses":{"200":{"description":"Successful","content":{"application/json":{"schema":{"$ref":"#/components/schemas/InitSaleResponse"}}}},"400":{"description":"Error","content":{"application/json":{"schema":{"$ref":"#/components/schemas/ErrorResponse"}}}}}}}},"components":{"parameters":{"ContentTypeHeader":{"name":"Content-Type","in":"header","required":true,"description":"Content type.","schema":{"type":"string"}}},"schemas":{"InitSaleRequest":{"type":"object","properties":{"amount":{"type":"number","description":"Amount."},"add_commission":{"type":"boolean","description":"Should the commission be added?"},"instalment":{"type":"integer","description":"Installment."},"card_holder_phone":{"type":"string","description":"Card holder phone."},"card_holder_mail":{"type":"string","description":"Card holder mail."},"description":{"type":"string","description":"Description."},"reference_no":{"type":"string","description":"Reference number."},"selected_agent_id":{"type":"string","description":"Selected agent id."},"callback_url":{"type":"string","description":"Deeplink will take you back to the mobile application."}}},"InitSaleResponse":{"type":"object","properties":{"payment_session_id":{"type":"string","description":"Payment session id."},"deeplink_url":{"type":"string","description":"Deeplink url."},"encryption_key":{"type":"string","description":"Encryption key."},"object_name":{"type":"string","description":"Object name."},"code":{"type":"integer","description":"Code."},"message":{"type":"string","description":"Message."}}},"ErrorResponse":{"type":"object","properties":{"object_name":{"type":"string","description":"Object name."},"code":{"type":"integer","description":"Code."},"message":{"type":"string","description":"Message."}}}}}}
```