Problem calling another Voxalot

[hddlab]

Hello
I have a Voxalot account and I have a fried that have another, we are having problems when I call him, sometimes the call shutdown with 30 seconds, another time does not conect, others conect but I can hear hin and he ca not hear me.
Some times when I use *010 and I call him, the call goes direct to voicemail.

When we use Gizmo and we call eachothers him using Gizmo and I using Voxalot we do not have this porblems also when we change- he with Voxalot an I using Gizmo same the connection is working.

We already did a lot of tests, and using all the Codecs, and we are getting same result all the time.

Someone here is facing something similar?
Someone here has any ideia of what can be?

Thank you very much for your attention and time

Jose Pinto