Connecting IP600H to AltiWare 4.0A?

[AltSol4]

AltiWare 4.0A have served us for some time. I want to add few IP600H phones and stay with the current version. The IP600H manual says that the phone would work with versions previous to AltiWare 4.6 but with some limitations. The IP600H phone first successfully registers and then request a disengagement from the AltiWare 4.0A (GateKeeper 4.0 and 4.6). Please see an IP trace log below. I suspect that the phone firmware version is the problem. I have tried firmware versions 1124, 1126, 1211, 1238 and 1242. Could an older IP600H firmware version work better? Has anyone been successful adding IP600H phones to AltiWare 4.0A? Any advice would help.

192.168.1.151 AltiServer 4.0A
192.168.1.152 IP600H


No. Source Destination Protocol Info
1 192.168.1.152 192.168.1.151 H.225.0 RAS: gatekeeperRequest
2 192.168.1.151 192.168.1.152 H.225.0 RAS: gatekeeperConfirm
3 192.168.1.152 192.168.1.151 H.225.0 RAS: registrationRequest
4 192.168.1.151 192.168.1.152 H.225.0 RAS: registrationConfirm
5 192.168.1.152 192.168.1.151 H.225.0 RAS: admissionRequest
6 192.168.1.151 192.168.1.152 H.225.0 RAS: admissionConfirm
7 192.168.1.152 192.168.1.151 H.225.0 RAS: disengageRequest
8 192.168.1.151 192.168.1.152 H.225.0 RAS: disengageConfirm
9 192.168.1.152 192.168.1.151 H.225.0 RAS: unregistrationRequest
10 192.168.1.151 192.168.1.152 H.225.0 RAS: unregistrationConfirm