El Phonebook como puedes ver si es aprovisionado en esos equipos:
<!-- ############################################################################## -->
<!-- ## Directory/Phonebook Management -->
<!-- ############################################################################## -->
<!-- # HTTP/HTTPS User Name -->
<!-- # String -->
<P6713></P6713>
<!-- # HTTP/HTTPS Password -->
<!-- # String -->
<P6714></P6714>
{IF network=LOCALLAN}
<!-- Enable Phonebook XML Download. # 0 - Disabled, 1 - Enabled, use HTTP, 2 - Enabled, use TFTP, 3 - Enabled, use HTTPS. Default is 0 -->
<!-- Number: 0, 1, 2, 3 -->
<!-- Mandatory -->
<P330>1</P330>
<!-- Phonebook XML Server Path -->
<!-- This is a string of up to 128 characters that should contain a path to the XML file. -->
<!-- It MUST be in the host/path format. For example: "directory.grandstream.com/engineering" -->
<P331>%%PROVLINKLOCAL.HOST%%:%%PROVLINKLOCAL.PORT%%%%PROVLINKLOCAL.PATH%%</P331>
{ELSE}
<!-- Enable Phonebook XML Download. # 0 - Disabled, 1 - Enabled, use HTTP, 2 - Enabled, use TFTP, 3 - Enabled, use HTTPS. Default is 0 -->
<!-- Number: 0, 1, 2, 3 -->
<!-- Mandatory -->
<P330>3</P330>
<!-- Phonebook XML Server Path -->
<!-- This is a string of up to 128 characters that should contain a path to the XML file. -->
<!-- It MUST be in the host/path format. For example: "directory.grandstream.com/engineering" -->
<P331>%%PROVLINK.HOST%%:%%PROVLINK.PORT%%%%PROVLINK.PATH%%</P331>
{ENDIF}
<!-- # Phonebook Download Interval (in minutes) -->
<!-- # Valid value range is 5-720. Default is 0 for disabled -->
<!-- # Number: 0, 5-720; -->
<P332>5</P332>
<!-- # Remove Manually-edited entries on Download. 0 - No, 1 - Yes. Default is 1 -->
<!-- # Number: 0, 1 -->
<!-- # Mandatory -->
<P333>1</P333>
<!-- # Import Group Method. 0 - Replace, 1 - Append. Default is 0 -->
<!-- # Number: 0, 1 -->
<!-- # Mandatory -->
<P8462>0</P8462>
<!-- # Sort Phonebook by. 0 - Last Name, 1 - First Name. Default is 0 -->
<!-- # Number: 0, 1 -->
<!-- # Mandatory -->
<P2914>0</P2914>
{IF ua=GRP2614,GRP2616}
<!-- # Phonebook Key Function. 0 - Default, 1 - LDAP Search, 2 - Local Phonebook, 3 - Local Group, 4 - Broadsoft Phonebook -->
<!-- # Number: 0, 1, 2, 3, 4. -->
<!-- # Mandatory -->
<P1526>0</P1526>
{ENDIF}
<!-- # Default search mode. 0 - Quick match, 1 - Exact match. Default is 0 -->
<!-- # Number: 0, 1. -->
<!-- # Mandatory -->
<P2970>0</P2970>
Si realmente no te muestra las extensiones locales de la central en el phonebook de esos teléfonos deberás revisarlo directamente con Grandstream, puesto que son ellos quien han desarrollado esas plantillas.
Un saludo!