An error occurred while trying to communicate with an external SFB user. I can't always make a call and can't add multiple participants to a conversation. In Event log on Edge Server we're have next error:
The following discovered partners are sending frequent invalid SIP requests to the Access Edge Server.
Traffic from these partners is restricted to 1 message per second as a security measure.
Certificate Subject: "subject 1"; Issuer: "US, DigiCert Inc, www.digicert.com, GeoTrust RSA CA 2018"; Serial Number: 0D59; Common Failures: OTHER(430,OTHER)=1 OTHER(4xx,OTHER)=1
Certificate Subject: "subject 2"; Issuer: "PL, Unizeto Technologies S.A., Certum Certification Authority, Certum Domain Validation CA SHA2"; Serial Number: 5D1B1; Common Failures: SUBSCRIBE(4xx,OTHER)=79
Certificate Subject: "subject 3"; Issuer: "US, Arizona, Scottsdale, "GoDaddy.com, Inc.", http://certs.godaddy.com/repository/, Go Daddy Secure Certificate Authority - G2"; Serial Number: 0097; Common Failures: SUBSCRIBE(4xx,OTHER)=23
Cause: Federated partners that were discovered through DNS SRV are sending frequent SIP requests that cause an error response from the local Skype for Business Server deployment.
Resolution: It is recommended that connections from these partners be blocked at the firewall.
We do not know if the events are related to this error. But they happened about the same time. Any help?