Iax trunk not always registered in an IP-PBX

hello Dear all,

i am facing a strange problem which is i have iax accounts that i can register in an IP-Phone or an ATA or IP-PBX but when i register one of this accounts in the IP-Phone or an ATA the TRunk will be always registered but when i register this same acount in an IP-PBX the trunk nwill sometimes registered and other times not without while in the IP-Phone or the ATA the trunk is always registered and stable .

its just that sometimes when i reboot the IP PBX the trunk will be registered.

i am sure many faced this problem …if any one can help about this he will make a great enhancement to the ip-pbx technologys.

given that i am sure about those iax accounts validity the exact problem in the iax registration is not always registered only on the IP-PBX

Thanks a lot in presence.