HPE OfficeConnect Switch 1920S JL382A not allowing and ipphone grandstream to register

Hello Team, 

I am wondering if you can help me out. 

I got two HPE OfficeConnect Switch 1920S JL382A and I am not able to register ip phone grandstream throught the switch. If I run an application in a computer as ip communicator everything workes fine. The issue is just with physical ip phones. 

I alredy did a factory default configuracion and updated the firmware of the switches to the latest version but the isuse is the same.  

I enable/disable LLDP-MED AND Auto voice VLAN with no luck. 

If I replace the switch to another one everyting works fine. 

We are using a single vlan(vlan 1) and for sure I am able to ping the pbx from the switch. 

Any help is wellcome. 

Regards,