Cisco Cisco IOS Software Release 12.4(4)T

For Cisco V.150.1 MER with third-party equipment interoperability - 

You must have Cisco IOS Release 15.6(2)T or later and Cisco Unified Communications 
Manager Release 10.5(2) or later.

You must have universalk9-mz image installed and running on ISR Generation 2s (ISR G2s) or 
VG350 and VG20xXM platforms

UC and security feature licenses are needed for ISR G2s

For Cisco V.150.1 MER (without third-party equipment interoperability) -

You must have Cisco IOS Release 15.1(4)M or later and Cisco Unified Communications 
Manager Release 8.6 or later

You must have adventerprisek9-mz installed on ISRG1 (28xx/38xx) or advipservicesk9-mz 
installed on VG22x platforms.

V.90 and V.92 are not supported in Cisco Legacy V.150.1 or in Cisco V.150.1 MER modem relay.

Secure Communication Between IP-STE 
Endpoint and Line-Side STE Endpoint

12.4(4)T
12.4(9)T

This feature was introduced in Cisco IOS Release 12.4(4)T.

In Cisco IOS Release 12.4(9)T, this feature was 
implemented on the following platforms: Cisco 2801, 
Cisco 2811, Cisco 2821, Cisco 2851, Cisco 3825, 
Cisco 3845, Cisco VG224.

Cisco V.150.1 Minimum Essential 
Requirements (MER)

15.1(4)M

This feature was renamed and enhanced to provide: 

V.150.1 MER modem relay support

RFC 2833 support for Events 32-35

T.38 Annex F support 

No-Audio Codec Support

Backward compatibility to existing V.150.1 
implementation

Cisco V.150.1 MER Enhancement

15.6(2)T

This feature was enhanced to provide interoperability with 
third-party equipment in a network.

In Cisco IOS Release 15.6(2)T, this feature was 
implemented only on the following platforms: Cisco 1921, 
Cisco 1941, Cisco 2901, Cisco 2911, Cisco 2921, Cisco 
2951, Cisco 3925, Cisco 3925E, Cisco 3945, Cisco 3945E, 
VG 310, VG 350, and VG20xXM platforms.