Can SIP peers make calls through the IAX channel?

Question

Asterisk

Hello.
Set up a connection between two servers via IAX.
However, clients connect to servers via SIP.
Can calls between clients of two servers go through the IAX channel? No need to forward sip ports.
This question is caused by the fact that in the book "Asterisk. The Future of Telephony", it is indicated:

This example assumes that you have configured a pair of IAX2 softphones, but if you have a SIP phone (or two) you can use that as well. Just remember that in this case, you will need to change the
Dial() application so that calls are directed to the SIP phone using the SIP protocol, and not IAX2 (that is, the Dial(IAX2/${EXTEN},30) line must be replaced with Dial( SIP/${EXTEN},30))

Why then do I need an IAX channel if the call still goes through SIP?

Answer 1

Client A calls its server A over SIP
Server A calls server B over IAX
Server B calls its client B over SIP It's
just a matter of proper routing/dialplan.