Are Skype for Business for PC and Mobile different?

Question

Asterisk

Hello. Need help with strange S4B behavior when integrating with Asterisk.
Scheme:
S4B FE + Med. = 111.70 S4B
Edge = 111.71
Asterisk Main = 217. (just an external interface, not an ISP)
{Asterisk Mediator (more on that later) = 111.14}

When we call from an S4B client on a computer , we (most likely) get a 401 (Unauthorized) error . The call is not visible in the Asterisk CLI, only in debug and tcpdump.
[2021-08-04 18:53:12] DEBUG[123492][C-000003b6]: chan_sip.c:3806 __sip_xmit: Trying to put 'SIP/2.0 401' onto TCP socket destined for 192.168.111.70:59975

BUT! When I call from a mobile phone through the S4B mobile client - everything works!
Why is this weird? Because even though S4B Mobile communicates with S4B Edge, the call still comes from the S4B Mediation Server (A\V). In both cases, in this scenario, the settings of the asterisk sip trunks and the S4B server trunks/policies are the same. However, we get different results .

In the case when both desktop and mobile clients work equally, the following scheme is used:
Asterisk Main 217.xxx <-IAX2-> Asterisk Mediator xx111.14 <-SIP-> S4B FE + Med xx111.70.

In this case, desktop and mobile clients work. But, you know, these are crutches. I'm asking for help to figure out why it dials from a mobile phone, when it doesn't from a desktop client. Here the option is that when he calls from a mobile phone, something does not work out in an asterisk, or vice versa.

I'm clarifying! Calls to Asterisk on S4B in any of the options work for any client.
In that case, question. What interferes with desktop client calls, why doesn't it interfere with mobile? I would appreciate any advice or help!

Technical information in the comment below the post