Technology
Physically, it has two rows of 23 pins, making 46 pins total. Three drawbacks of AMR are that it eliminates one Peripheral Component Interconnect (PCI) slot, it is not plug and play, and it does not allow for hardware accelerated cards (only software-based).
Technologically, it has been superseded by the Advanced Communications Riser (ACR) and Intel's own Communications and Networking Riser (CNR). However, riser technologies in general never really took off. Modems generally remained as PCI cards while audio interfaces were integrated on to motherboards.
Recently motherboard manufacturer ASRock has resurrected this concept, introducing the High Definition Multimedia Riser (HDMR) slot on most of its motherboards. Little information is available, but drivers on the Asrock website indicate the existence of V.92 modem cards for this standard. It is not clear how HDMR differs from AMR, if indeed at all.
Read more about this topic: Audio/modem Riser