Should the 3CX SIP port be filtered by firewall ACL rules for security?

Filtering the 3CX SIP port through firewall ACL (Access Control List) rules is essential for enhancing the security of the communication system. By implementing filtering, you limit access to the SIP port only to authorized IP addresses or networks. This helps to mitigate the risk of unauthorized access, which can lead to threats such as SIP attacks, toll fraud, or other forms of security breaches where malicious users may attempt to hijack calls or gain control over the system.

Moreover, firewalls are designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. Filtering the SIP port ensures that only legitimate traffic that meets the specified criteria is allowed through, providing an additional layer of defense against potential vulnerabilities associated with open ports. By adopting a proactive security posture with firewall filtering, you protect not just the SIP communications but the entire VoIP infrastructure from various cyber threats.

The other options suggest different approaches to managing the SIP port, but leaving it open or only filtering for remote access does not align with best security practices, as it could expose the system to unnecessary risks. Similarly, stating that filtering is unnecessary undermines the importance of safeguarding the network environment in today's landscape of increasing cyber threats.