Brekeke Establishing Interface to AWS

1. Brekeke Product Name and Version: RSS 3.10.5.6

2. Java version:11.0.5

3. OS type and the version: Server 2019

4. UA (phone), gateway or other hardware/software involved: Dial back to Rauland from CUCM

5. Your problem:
We have an existing Dial back integration from on-premises Cisco Call Manager (Software Version 11.5), working without issue. We tested a new SIP trunk from Cisco Data Center CUCM (Software Version 14), and the calls are failing, with a Call Leg cannot be established error.

In the Wireshark, we have found that the call is failing because RSS is adding a Contact and Record Route address of 52.223.6.9, which is a Public IP for AWS (awsglobalaccelerator.com)when the 200 OK comes from Rauland to RSS to send back to CUCM. Some more checking found that this IP is showing as an interface on RSS SIP Status page.

Ipconfig on the server does not list this IP.
This IP is not added/configured within the RSS setting.
The initial Invite from CUCM does not reference this IP.

We are going to try blocking this IP from the interfaces with CONFIGURATION>ADVANCED tab: the verbiage of the command is: net.net1.interface-restrict=*IPAddressOfTheNIC* as a troubleshooting step

But the customer wants us to establish a root cause of why this interface is showing in the first place. Any ideas on how this IP is getting introduced, or a next step to troubleshoot?

Here is the data flow we are seeing:
1. Invite come in from CUCM to RSS, no reference to 52.223.6.9 found in wireshark.

2. RSS sends 100 Trying back to CUCM, no reference to 52.223.6.9 found in wireshark.

3. RSS forwards the Invite to a Load Balancer, to distribute to Rauland app servers, no reference to 52.223.6.9 found in wireshark.

4. Load Balancer sends 200 OK back to RSS, no reference to 52.223.6.9 found in wireshark.

5. **RSS then forwards the 200 OK to CUCM, with Contact and Record-Route @52.223.6.9 added.**

6. After 3 re-tries, CUCM returns Call Leg/Transaction Does Not Exist error.

Are you sure no "52.223.6.9" at [Interface address 1] in [Configuration]->[System] page?

If you execute, "iflist" command at [Tools]->[Command] page, how is this IP address shown?

Does this IP address physically face to CUCM? or Load Balancer?

Are you sure no "52.223.6.9" at [Interface address 1] in [Configuration]->[System] page?
- Yes

If you execute, "iflist" command at [Tools]->[Command] page, how is this IP address shown?
- G:52.223.6.9 : domain: [<customer domain>.com]

Does this IP address physically face to CUCM? or Load Balancer?
- Not Sure, we do not know where or how this interface IP is getting introduced to the server.

> - G:52.223.6.9 : domain: [<customer domain>.com]

It means you have a setting for this domain under the [Domains] page.
Because this domain's IP address is 52.223.6.9 and it is a public IP address, the SIP server puts it in Contact URI if 200 OK is sent to another public IP address.

Do you have any reason to set the domain under [Domains] page?