You are tasked with implementing a 1000-phone remote access solution, where phones will traverse a WAN edge router. Assuming all of the following features are supported in a hardware- assisted manner,

Encryption algorithms such as AES involve multiple iterative rounds of substitution, permutation, and XOR operations that require significantly more processing cycles than simple encapsulation or stateful lookup operations, even when offloaded to dedicated crypto hardware. The inherent computational depth of block cipher processing means encryption consistently adds more latency than the other listed functions when applied to delay-sensitive VoIP packets traversing a WAN edge router.

Stateful firewall inspection involves connection table lookups that are very fast with hardware assist and add far less delay than cryptographic processing.

MPLS encapsulation is a straightforward label-pushing operation with negligible processing overhead.

GRE encapsulation simply prepends a fixed-size header to the packet, requiring minimal processing and adding only marginal delay.