[cisco-voip] interface vlan x give me Unrecognized command

[Ahmed Abdullahi]

Dumb question I know, but I can't figure it out.  When I run

router(config)# interface vlan 61

I get "invalid input detected at 'vlan'?

I'm running c3725-adventerprisek9_ivs-mz.124-15.T6

Thanks.