Flexisip as proxy with Freeswitch behind

[softer]

Hi!
I'm trying to configure flexisip as proxy in front of Freeswitch for sending push notifications.
I made a lab (2 VMs) for it with a fresh install both of them.
Freeswitch work fine (2 accounts, calls works), but Flexisip not.
Registration works, calls from Linphone (which is connected to Flexisip) goes for MicroSIP (wich is connected directly to Freeswitch), but from MicroSIP to Linphone - not...

I see INVITE into Flexisip log and I see ACK there. But Freeswitch says "Originate Failed. Cause: MANDATORY_IE_MISSING" and stops call.

What I'm doing wrong?

My Flexisip config:

[global]
transports=sip:*;transport=tcp
log-level=debug
# default-servers=proxy

[cluster]
[mdns-register]
[event-logs]
[stun-server]
enabled=false
[presence-server]
enabled=false
[conference-server]
[regevent-server]
[module::DoSProtection]
enabled=false
[module::SanityChecker]
enabled=false
[module::GarbageIn]
enabled=false
[module::Capabilities]
enabled=false
[module::Authentication]
enabled=false
[module::Redirect]
enabled=false
[module::RegEvent]
enabled=false

[module::Presence]
enabled=false
[module::StatisticsCollector]
enabled=false
[module::PushNotification]
enabled=false
[module::MediaRelay]
enabled=false
[module::Transcoder]
enabled=false
[module::GatewayAdapter]
enabled=false

[module::NatHelper]
enabled=true
filter=
contact-verified-param=verified
fix-record-routes=true
fix-record-routes-policy=safe

[module::B2bua]
enabled=false
[inter-domain-connections]
[b2bua-server]
[b2bua-server::trenscrypter]
[b2bua-server::sip-bridge]

[module::Registrar]
enabled=true
reg-domains=*
reg-on-response=true

[module::Forward]
enabled=true
routes-config-path=/etc/flexisip/routes.conf
add-path=true
default-transport=udp
params-to-remove=

[module::Router]
enabled=true
filter=(is_request && request.uri.params contains 'doroute') || is_response
fork-late=true

[module::ContactRouteInserter]
enabled=true
insert-domain=true