560M (M675I)
By Aastra Telecom Technologies

The 560M expansion module is designed to increase the power and flexibility of the 5i Series SIP telephones. Up to three modules can be used with the 57i or 57i CT telephone to create a powerful, feature rich console option. The 560M shares power and signaling with the phone, eliminating the need for additional wiring. ... 

16-Channel DSP Module for NM-HDA
By Cisco Systems

The 16-channel DSP Module provides enterprises, managed service providers and service providers the ability to directly connect the PSTN and legacy telephony equipment to Cisco 2600, 2800, 3600, 3700, and 3800 Series access routers. This provides immediate multi-service advantages, such as telephony toll bypass, new packet telephony applications, and full gateway integration within a Cisco AVVID (Architecture for Voice Video and Integrated Data) IP telephony architecture. ... 

536M (M670I)
By Aastra Telecom Technologies

The 536M expansion module is designed to increase the power and flexibility of the 5i Series SIP telephones. Up to three modules can be used with the 57i or 57i CT telephone to create a powerful, feature rich console option. The 536M shares power and signaling with the phone, eliminating the need for additional wiring. ...