Forbidden when trying to call on snom using virtual IP

Hi there,

i’m quite new to asterisk and trying to use keepalived to have HA.
Here is my setup

asterisk 1 voice lan :
asterisk 2 voice lan :

Keepalived virtual IP : (only asterisk 1 is alive, then .1 is on .11 server)

Snom 720 phone, firmware 8.7

When registering phone on all is ok
But when registering on .1 and doing a call i get a forbidden message on the phone

Bellow is what i get when i call 109 (franck) from 108 (alex)
On phone 108 i get a "forbidden 109"
On console, i get a :

== Using SIP RTP CoS mark 5
[Jun 2 11:09:42] WARNING[1114][C-0000000c]: chan_sip.c:33951 process_crypto: Ignoring crypto attribute in SDP because RTP transport is insecure
– Executing [109@sip-internal:1] Verbose(“SIP/108-0000000e”, “1,caller ID num = , en sip”) in new stack
caller ID num = , en sip
– Executing [109@sip-internal:2] Dial(“SIP/108-0000000e”, “SIP/109,10”) in new stack
== Using SIP RTP CoS mark 5
– Called SIP/109
[Jun 2 11:09:42] WARNING[1114][C-0000000c]: chan_sip.c:24037 handle_response_invite: Received response: “**Forbidden” from ‘“alex” sip:108@**;tag=as24ab52f4’
== Everyone is busy/congested at this time (1:0/0/1)
– Executing [109@sip-internal:3] Hangup(“SIP/108-0000000e”, “”) in new stack
== Spawn extension (sip-internal, 109, 3) exited non-zero on ‘SIP/108-0000000e’

What is weird is that the forbidden comes from alex, the caller (see bold line). ANd we can see that message comes from .11 not .1, maybe this is what snom do not like… Is there a way to solve that ?

Thank you very much

nobody has an idea about that ?