![]() ![]() Make sure that your SBC certificate is not self-signed and that you got it from a trusted Certificate Authority (CA). To enforce stricter security, enable TLS 1.2. This situation might occur if you’re using an older version of TLS. SBC doesn't receive a "200 OK" response from SIP proxy SIP options issuesĪfter the TLS connection is successfully established, and the SBC is able to send and receive messages to and from the Teams SIP proxy, there might still be problems that affect the format or content of SIP options. The status of SBCs that are in a derived trunk model are based on the main SBC. In a hosted model, SIP options should be sent from only the hosted SBC. This step confirms that the SBC is healthy.Īs the final step, the SBC is marked as Active in the Microsoft Teams admin center. The SIP proxy sends SIP options to the SBC FQDN that is listed in the Contact header of the SIP options received from the SBC.Īfter receiving SIP options from the SIP proxy, the SBC responds by sending a 200 OK message. If the SBC FQDN is detected and recognized, the SIP proxy sends a 200 OK message by using the same TLS connection. If the FQDN information is not detected there, the SIP proxy checks the Contact header. If the request is valid, the TLS connection is established, and the SBC uses it to send SIP options to the SIP proxy.Īfter it receives SIP options, the SIP proxy checks the Record-Route to determine whether the SBC FQDN belongs to a known tenant.If the request is not valid, the TLS connection is closed and the SIP proxy does not receive SIP options from the SBC.The SIP proxy checks the connection request. The SBC sends a TLS connection request that includes a TLS certificate to the SIP proxy server Fully Qualified Domain Name (FQDN) (for example, ). ![]() This article lists some common issues that are related to SIP options and TLS certificates, and provides resolutions that you can try. An SBC is not configured correctly for Direct Routing.A TLS certificate experiences problems.Such issues are most likely caused by either or both of the following conditions: The SBC is marked as inactive in the Microsoft Teams admin center.Transport Layer Security (TLS) connections problems occur.Session Initiation Protocol (SIP) options are not received.This issue is patched in version 1.10.7.When you set up Direct Routing, you might experience the following Session Border Controller (SBC) connectivity issues: The attack does not require authentication or any special foothold in the caller's or the callee's network. ![]() By abusing this vulnerability, an attacker is able to disconnect any ongoing calls that are using SRTP. The call disconnection occurs due to line 6331 in the source file `switch_rtp.c`, which disconnects the call when the total number of SRTP errors reach a hard-coded threshold (100). This issue was reproduced when using the SDES key exchange mechanism in a SIP environment as well as when using the DTLS key exchange mechanism in a WebRTC environment. When a media port that is handling SRTP traffic is flooded with a specially crafted SRTP packet, the call is terminated leading to denial of service. This attack can be done continuously, thus denying encrypted calls during the attack. When handling SRTP calls, FreeSWITCH prior to version 1.10.7 is susceptible to a DoS where calls can be terminated by remote attackers. ![]() FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. ![]()
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