4 bases not receive calls

[bluetel]

hi tks for your reply

My customer have 4 bases and 4 handset. All are on last firmware (handset and base)26.50.20 and 25.50.20

All handset are registered on 1 base, and can register to 3 others. When call is generated per 3cx, we can see sip trame go to all base. it ring on handset 1 time and next stop. only 1 ringing and next 3cx receive status from base -> busy or reason User Requested

here the answer of base

23/06/2014 09:33:37:581 | Cancelling with:
CANCEL sip:146@192.168.1.244:5064 SIP/2.0
Via: SIP/2.0/ ;branch=z9hG4bK-d8754z-3345f329a124da79-1---d8754z-;rport
Max-Forwards: 70
To: <sip:146@192.168.1.6>
From: "xxxx"<sip:120@192.168.1.6:5060>;tag=001c6130
Call-ID: ZWI2MDIyODM2MWIzN2NiODMwOGU1YjYzY2E5Y2E5OWY.
CSeq: 1 CANCEL
Reason: SIP ;cause=200 ;text="User hangup"
Content-Length: 0

see that :
23/06/2014 09:33:37:581 | Reason: SIP ;cause=200 ;text="User hangup"

but my customer never hangup.

tks advance for your help