Wireshark · Wireshark-dev: Re: [Wireshark-dev] Feature Request for EDITCAP - Selecting by IP Address and Port Number

[Bill Meier <wmeier@xxxxxxxxxxx>]

>  What I need to do is to be able to extract out a specific VoIP call using
> UNISTIM that spans multiple capture files based on IP Address and
> Source and/or Destination Port and possible a within a specific time frame.

Altho I haven't tried this, I think the following should work:

tshark -r <input file> -R <read filter> -f <output file>

(You might need to write a script to run tshark on each of multiple 
files and then use mergecap to combine the output files).

See the tshark help or manpage for additional information.