Amazon Connect Outbound Call Cross-Line

I apologize, but I'm afraid there seems to be a misunderstanding in your description of the issue. Based on the information provided in the Amazon Connect documentation, the behavior you're describing is not a standard feature or known issue with Amazon Connect's outbound calling functionality.

Amazon Connect is designed to handle multiple concurrent calls efficiently, and there's no inherent limitation that would cause cross-line issues after a specific number of calls. The routing profiles and queues you've set up should not cause this type of problem.

However, let's consider a few points that might help address your concern:

1. Routing profiles in Amazon Connect are used to link agents to queues and specify which channels (like voice or chat) agents can handle. They also determine how many contacts an agent can handle simultaneously for each channel.

2. When setting up outbound calling, it's important to ensure that your Amazon Connect instance is properly configured to allow outbound calls and that you've set up the outbound caller ID correctly.

3. The number of concurrent active calls per instance is not typically limited to 10. Amazon Connect can handle a much higher volume of concurrent calls, depending on your service quota.

4. Cross-line issues are not a known problem in Amazon Connect when the number of concurrent calls increases.

Given the unusual nature of the issue you're experiencing, I would recommend the following steps:

1. Double-check your routing profile and queue configurations to ensure they are set up correctly.
2. Verify that your outbound calling setup, including caller ID, is properly configured.
3. Check your service quotas to ensure you're not hitting any limits.
4. If the problem persists, it would be best to contact AWS Support for a more in-depth investigation of your specific setup and the issue you're encountering.

They will be able to look into the specifics of your instance and provide more tailored assistance for this unusual behavior.
Sources
Set up routing in Amazon Connect - Amazon Connect
Set up outbound calling in Amazon Connect - Amazon Connect
Make outbound calls using the Contact Control Panel (CCP) - Amazon Connect

A few things that should help narrow this down.

First, your "10 concurrent calls" figure is correct. The default concurrent active calls per instance quota is 10. But going over a concurrency limit makes calls fail or return a busy tone, it doesn't splice two live calls together, so that quota isn't what's producing the cross-line. It showing up around the 5th or 6th call is more likely a symptom than the cause.

The next thing worth anchoring on is how the calls are being placed, because it changes the whole diagnosis. In Amazon Connect a single agent can only be on one voice call at a time (voice concurrency is fixed at 1, both minimum and maximum). So if 5-6 calls are genuinely live at once, either there are 5-6 separate agents each on their own call, or the calls are being placed programmatically through StartOutboundVoiceContact or an outbound dialer rather than by agents in the CCP. Pinning that down first is the most important step.

Here's why that matters: cross-line or audio bleeding between separate calls doesn't come from routing profiles or queues. Those only decide who gets routed where, not how the audio is handled, so changing queue setup won't fix it. This symptom lives at the softphone/session layer. The usual things to rule out:

Any chance the same Amazon Connect user is signed in from more than one place at once, whether that's shared credentials or the CCP open across multiple tabs or devices. Give every agent their own unique user and confirm no single account is active in two sessions. A custom or embedded CCP built on amazon-connect-streams. If the integration reuses one softphone session or doesn't keep each contact's media separate, concurrent calls can cross. Each live call needs its own cleanly isolated contact and media session. To actually root-cause it, grab the contact IDs of two calls that crossed, pull their contact records, and cross-check the StartOutboundVoiceContact entries in CloudTrail to see whether those calls share anything they shouldn't. That's also exactly what AWS Support will ask for, so opening a case with specific crossed-call contact IDs will move a lot faster than a general description.

Short version: your 10 figure is right but isn't the cause, a single agent is only ever on one voice call so confirm how these are being dialed, and cross-line audio points to shared logins or a softphone/session issue rather than your queues.