Search for specific word in a packet

RouterOS Wireless Networking
1

I want to look if a certain packet coming from one local device that contains a certain word and than react by sending an output pin high on the router
or sending a packet to a local esp8266 to react upon.

The word is “callStatus” and it is a HTTP TCP packet about 300-400 in size.

How would i go about doing this?

2

/ip firewall filter add action=“yor action” chain=input content=“your words”