: Enhanced support for dual-stacking, IPv6 tunneling, and OSPFv3.

Running a 15.2(1)T Advanced Enterprise image is resource-intensive. To avoid boot loops or performance degradation, ensure your hardware meets the following minimum requirements : Requirement Specification Minimum 512 MB (Recommended: 768 MB or 1 GB) Flash Memory Minimum 256 MB Supported Models 2811, 2821, 2851

: Supports Cisco Unified Communications Manager Express (CME) version 8.x, allowing the router to act as a PBX for VoIP networks.