wireshark/tcpdump extract a gsm call audio

[reginaldosalles]

you can record a inbound gsm call audio using bladerf? using
wireshark/tcpdump in gsmtap interface it is possible to extract the inbound
sgm call audio? i can do this in wireshark using sip for outbound gsm calls
(rtp/stream analysis). but it is possible in inbound gsm calls without use sip
or iax? need more info about it and how to extract a gsm call audio from .cap
capture files.