IP Multimedia Subsystem (IMS) is a standardized Next Generation Network (NGN) architecture, used to provide users access to different services even in case of roaming. Although this architecture is deployed in cellular (mobile) networks, the latter represents several limitations, notably in terms of security. To overcome this inadequacy, IPsec protocol can be deployed between user equipment (UE) and Proxy Call Session Control Functions (P-CSCF). This solution has certain limitations in terms of reliability, i.e. the same security policy deployed between UE and P-CSCF will be applied to any type of the client traffic. In other words, if network performances are critical and the security policy deployed requires high processing, the transported traffic of real-time characteristic will suffer from a quality deterioration. In this work, we propose a new approach for the adaptive management of the IPsec protocol for IMS architectures, called Smart Adaptive Security for IMS, an acronym for SAS-IMS.