Any SIP Application Layer Gateway (SIP ALG) on your network must be disabled in your firewall. This is necessary to ensure that SIP packets are successfully passing outbound from and inbound to your CyberData product(s).
Many firewalls and routers have SIP-specific settings that manipulate how SIP traffic is handled, with the intent to help alleviate traditional issues that applications with specific addressing requirements like SIP have with NAT traversal. This function can have different names (SIP ALG, SIP Helper, SIP Inspection, SIP Transformations, etc.), but ultimately, they all perform a similar function — identifying SIP packets and manipulating them.
If your firewall or router does not have an option to disable SIP ALG, that does not mean that it is not running; it just means you cannot disable it. The only way to truly confirm if it is enabled or not would be to contact the vendor and have them verify whether a SIP Application Layer Gateway is running on the device. If it is running, ask them how that can be disabled.