Security Notification Systems/ Mass Notification Systems

What are the best Security Notification System that can integrate with IP CCTV/Access Control systems/Intrusion systems and can send alarms over SMS, whatsapp, PA systems and IP telephony systems such as Avaya/Cisco/Mitel?

We been dealers of AtHoc for some time but I don't think we've actually sold any systems. Their systems does exactly what you are asking and the demo is very impressive.

integrate with IP CCTV/Access Control

What integration are you seeking?

On the Mass Notification side integration is often with the fire alarm panel.

I am not certain what integration would exist from CCTV/Access control to a "security notification" system.

Another candidate within the unified notification space would be Alertus.

Talkaphone, Codeblue and Commend may be an option.