match protocol rtp audio on a 871?

[melaniemaillet]

Hi

I tried to add match protocol rtp audio to my class map, but it seems the box doesn't like that cmd

router(config)#class-map match-any REAL-TIME
router(config-cmap)#match protocol rtp audio
                                                   ^
% Invalid input detected at '^' marker.

I am using an 871 cisco router with the IOS version : c870-advipservicesk9-mz.124-6.T5.bin

Could it be the IOS not accepting that cmd?

Thanks in advance