PAP2T - Can't make 2 simultaneous calls using ulaw

Hi, we have 2 different Linksys PAP2T devices and we know that they can make 2 simultaneous calls but only one using g729 codec due to licensing and processor consumtion. The problem is that we can't make 2 calls at the same time even uaing ulaw ! We verified twice that device must be abble to make make/calls on both lines without any problem, so we think this i a configuration issue. We want an phone VoIP technical expert to check our device via teamviewer and also talk by voice (skype or direct phone) and make thig work. We think this is a 30 minutes job, but anyway we will alow a 2h job. Please, only bid very expertise techs on VoIP phones area.