Cisco Cisco IOS Software Release 12.4(23)

1-port ADSL over POTS with dying gasp (WIC-1ADSL-DG) Cisco 2610XM, Cisco 2611XM, 

Cisco 2620XM, Cisco 2621XM, 
Cisco 2650XM, Cisco 2651XM,
Cisco 2691

1-port G.SHDSL WAN interface card (WIC-1SHDSL)

Cisco 2610XM, Cisco 2611XM, 
Cisco 2620XM, Cisco 2621XM, 
Cisco 2650XM, Cisco 2651XM,
Cisco 2691

1-port G.SHDSL with 4-wire support WAN interface card 
(WIC-1SHDSL-V2)

Cisco 2610XM, Cisco 2611XM, 
Cisco 2620XM, Cisco 2621XM, 
Cisco 2650XM, Cisco 2651XM,
Cisco 2691

1-port G.SHDSL with 4-wire support WAN interface card 
(WIC-1SHDSL-V3)

Cisco 2610XM, Cisco 2611XM, 
Cisco 2620XM, Cisco 2621XM, 
Cisco 2650XM, Cisco 2651XM,
Cisco 2691

1-port ISDN BRI S/T interface (requires external NT-1) 
(WIC-1B-S/T, WIC-1B-S/T-V3)

All Cisco 2600 series platforms

1-port ISDN BRI (NT-1) U (WIC-1B-U, WIC-1B-U-V2)

All Cisco 2600 series platforms

1-port 56/64-kbps DSU/CSU

All Cisco 2600 series platforms

1-port T1/fractional T1 with DSU/CSU WAN interface card 
(WIC-1DSU-T1, WIC-1DSU-T1-V2)

All Cisco 2600 series platforms

1-port high-speed serial (up to 2.048 Mbps) (WIC-1T)

All Cisco 2600 series platforms

2-port dual high-speed serial (up to 8 Mbps; asynchro-
nous/synchronous support) (WIC-2T)

All Cisco 2600 series platforms

2-port asynchronous/synchronous (up to 128 kbps) 
(WIC-2A/S)

All Cisco 2600 series platforms