Resolve Content Security Policy blocks in an IllyVoIP SDK integration

A browser Content Security Policy can block an IllyVoIP SDK script, token request, signaling connection or media asset. Identify the blocked resource and responsible directive before changing the policy. A CSP error is not a reason to disable the site’s protections globally.

Start with the official IllyVoIP Webphone SDK 1.4.2 bundle and one managed phone owner. Your backend must authorize the signed-in user’s SIP identity and issue the short-lived browser token. The examples extend your application; they do not change the hosted Portal phone.

1. Capture the first relevant violation

1. Open developer tools on your own integration and reproduce the failed enable or connection step.
2. Read the Console violation and Network request, noting the directive, blocked URL and document origin.
3. Check the actual response headers on the affected document, including parent and iframe pages.
4. Remove tokens, customer identifiers and private query strings before sharing diagnostics.

Several enforced policies can apply at once. Adding a more permissive header does not cancel an existing restrictive one. A report-only policy records violations but does not itself permit resources blocked by an enforced policy.

2. Match the blocked resource to its purpose

• Script loading: inspect script-src and the location of your matching SDK facade and browser runtime.
• Token/bootstrap HTTP requests: inspect connect-src for the authenticated backend and actual required API origin.
• Secure WebSocket signaling: inspect connect-src for the current bootstrap-provided WSS origin.
• Owned ringtone or remote audio files: inspect media-src and the real asset URL.
• Embedding: inspect the parent frame-src and the phone document’s frame-ancestors separately.

The SDK derives runtime loading and connection data from its configuration and bootstrap. Inspect those current values privately; do not copy an old infrastructure hostname into a permanent policy. Do not expose the complete bootstrap just to find a WebSocket host.

3. Test a narrow policy in a controlled environment

Content-Security-Policy-Report-Only:
  default-src 'self';
  script-src 'self';
  connect-src 'self' https://YOUR-TOKEN-ORIGIN wss://YOUR-SIGNALING-ORIGIN;
  media-src 'self';
  object-src 'none';
  base-uri 'self';

This is a diagnostic starting point, not a deployable policy. Replace the placeholders and account for the rest of your application. The HTTP header is one header value; line breaks above are for readability. Report-only mode does not weaken an already enforced policy. Use a controlled environment to compare the intended policy before a production change.

For inline application code, use your framework’s reviewed nonce or hash approach, or move the code to an approved external file. Do not add unsafe-inline, unsafe-eval, broad wildcards or every observed domain just to silence the console. Allow a resource only after confirming why your integration needs it.

4. Separate other browser failures

CORS rejection, failed authentication, microphone permission, autoplay restrictions and unavailable signaling are different problems. A successful CSP adjustment does not fix them. Inspect the actual next error rather than repeatedly widening the policy. Likewise, WebRTC media transport problems cannot be diagnosed from connect-src alone.

5. Verify the full lifecycle

1. Reload a fresh session and confirm the intended SDK files load.
2. Enable the phone and inspect the token and signaling steps.
3. Check any owned tone asset and incoming-call UI.
4. Test cleanup, logout and token refresh, not just initial page load.
5. Keep an enforced-policy regression check in your application’s deployment review.

Begin with local mocked requests and policy tests. For actual call quality, arrange an authorized end-to-end test on the supported browser and network. Save the before/after policy and sanitized violation evidence so an unrelated site break can be reversed deliberately.

Related guides

• Add browser calling with the Webphone SDK
• Manage the IllyVoIP WebRTC Phone SDK lifecycle in React
• Handle browser-token refresh in a long-running IllyVoIP SDK session

Reference

Current instructions and technical reference: MDN: Content Security Policy, MDN: connection policy.

Reviewed 13 October 2026 against the current IllyVoIP controls, implementation and applicable references. Available options depend on account permissions and service state.