What is port 1024 on Asterisk and why does it indicate that it needs to be answered?

Question

Asterisk

There is an ancient Asterisk 1.6.2.20
For some reason, when working through nat, it indicates waiting for packets not at 5060, but at 1024, which does not look. You have to wrap packets on the natom router from this port to asterisk 5060.
in [general] I have
externip=<external ip>
nat=force_rport,comedia
Package example:
Call-ID: [email protected]<asterisk local ip>
CSeq: 102 INVITE
Via: SIP/2.0/UDP <asterisk local ip>:5060 ;received=<external ip>;rport= 1024 ;branch=z9hG4bK602441b6
Contact: :65476;transport=udp>