> For the complete documentation index, see [llms.txt](https://docs.coda.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coda.co/codapay/codapay-integration-faq/hosted-payment-page-api/post-integration.md).
# Post-Integration
#### 1. Where can I configure the Transaction (Callback and Redirect) URLs?
* Sandbox environment URLs can be configured in Publisher Portal -> Integration -> Codapay -> Sandbox Configuration. Refer to [Sandbox Configuration and Production Configuration](/codapay/integration-guides/testing-guide/sandbox-configuration-and-production-configuration.md)
* Production environment can be configured in Publisher Portal -> Integration -> Codapay -> Production Transaction URLs.
***
#### 2. Where can I add the Whitelist IP address?
Proceed to Publisher Portal -> Integration -> Codapay -> API Keys -> Action to insert the IP address.
> Enter multiple IP Addresses separated by comma.
New merchants' view
Existing merchants' view
***
#### 3. What are the IP addresses used for the Codapay Callback System?
* [Filtering Codapay IP](/codapay/integration-guides/security-guidelines.md#filtering-codapay-ip)
***
4. **I encounter ERR\_UNKNOWN\_URL\_SCHEME when proceeding to the payment**
Please make sure that you handle the redirections properly when using Webviews, refer to [Display the Hosted Payment Page](/codapay/hosted-payment-page-integration/display-the-hosted-payment-page.md#special-considerations-for-webviews)
***
#### 4. I encountered error 205 in the production environment. What steps should I take?
This error occurs when a merchant’s sandbox system is pointing to Coda’s production system, but the status in Coda’s production environment is still set to "Testing." In this scenario, the merchant should switch their airtime URL to the sandbox URL and continue testing.
Additionally, this error can happen if a merchant’s production system correctly points to Coda’s production system, but the merchant account is not yet active in Coda’s production environment. In such cases, partners should contact the Codapay Support Team to activate your account.
***
#### 5. I don't have a local wallet/account, any testing credentials I can use in the Production Environment?
It is recommended that merchants complete the testing in the sandbox environment before using real money for testing, as **Refunds Are Not Available**.
The purpose of testing in the production environment is to ensure that the callback delivery is successful. Therefore, it is sufficient to select 1 or 2 channels to test in each country.
For channels that cannot be tested, merchants should ensure that they are properly configured and that the payment page is successfully displayed.
🟠If merchants require assistance from Coda for real money testing, please:
{% hint style="info" %}
* **Notify Coda's technical team 1 business day in advance** to allocate resources and manpower. \[**Not available on Weekend**]
* Coda technical team support from **9 am to 6 pm**, **GMT +8**
{% endhint %}
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