This Frequently Asked Questions (FAQ) document provides concise answers and guidance for using the GCC PBX module. It is intended to assist administrators and users in resolving common issues and understanding key features.
Product Overview & Specifications
GCC PBX is an IP PBX software module integrated into Grandstream GCC convergence devices. It provides enterprise telephony features while running alongside routing, switching, and security services on the same platform.
The GCC601x series targets small deployments with lower user and call capacity, while the GCC602x series supports higher concurrency, larger user counts, and more demanding PBX workloads.
No. All GCC601x and GCC602x devices include a free standard PBX package by default. This allows the system to operate immediately without any license purchase, within the included user and call capacity limits.
The GCC601x series includes a free standard package supporting up to 24 users/extensions and 8 concurrent calls. An optional UC-50 SMB upgrade package (one-time license) increases capacity to up to 50 users/extensions and 12 concurrent calls, while retaining all UCM6300 series PBX features.
In addition to the standard and SMB upgrade packages, GCC601x series PBX supports optional add-on licenses that allow administrators to further increase the number of users/extensions and concurrent calls beyond the base upgrade limits.
For detailed pricing information on GCC PBX upgrade and add-on licenses, please refer to the official pricing page.
The GCC602x series includes a free standard package supporting up to 50 users/extensions and 16 concurrent calls. With the UC-200 SMB upgrade package (one-time license), the system can scale up to 200 users/extensions and 48 concurrent calls, with full UCM6300 series PBX functionality.
In addition to the standard and SMB upgrade packages, GCC601x series PBX supports optional add-on licenses that allow administrators to further increase the number of users/extensions and concurrent calls beyond the base upgrade limits.
For detailed pricing information on GCC PBX upgrade and add-on licenses, please refer to the official pricing page.
No. All PBX add-on licenses are one-time purchases, valid for the lifetime of the product. There are no recurring fees for additional users or concurrent call capacity.
GCC PBX supports SIP extensions for IP phones, ATAs, and software-based SIP clients. It also supports WebRTC-based extensions through the Wave application, enabling users to place and receive calls from browsers and mobile devices. Unlike the UCM63xx series, GCC PBX does not support IAX extensions.
GCC PBX supports SIP trunks for connectivity to ITSPs and service providers. Both registration-based and peer SIP trunks are supported. Analog trunks are not supported, as GCC devices do not include FXO interfaces.
Setup & Activation
To access the GCC PBX Web UI, connect to the GCC device’s management interface using its IP address and log in with administrator credentials. From the main system interface, navigate to the IPPBX module to access PBX configuration and management pages.
No. The PBX module is disabled by default on GCC devices. Administrators must manually enable the IPPBX module from the system module management interface during initial setup.
When enabling the PBX module for the first time, a VLAN segment must be selected, and an IPv4 address must be assigned to the PBX service.
Yes. GCC PBX supports migration from UCM63xx series IP PBX systems by converting compatible backup files using GDMS (Cloud Storage→Convert Config File). Backup conversion is supported for UCM63xx devices running firmware version 1.0.27.x or later.
After conversion, the restored configuration can be applied to the GCC60xx PBX. Backup files from earlier UCM firmware versions are not supported and must be upgraded before conversion.
The GCC Overview (Home) page shows the status of the PBX module, including whether it is enabled or disabled and the IP address assigned to the PBX service.
No. Currently, the PBX IP address cannot be modified directly after the PBX module has been enabled. To change the PBX IP address, the PBX module must be disabled and then re-enabled, at which point a new IP address can be assigned.
The Existing PBX configuration will remain intact; however, it is strongly recommended to generate a full PBX backup before disabling the module to avoid any unexpected data loss.
No. A system reboot is not required after enabling the PBX module. Once the module is enabled and the IP address is assigned, the PBX service will start automatically and become accessible without restarting the GCC device.
Call Management & Advanced Features
Active calls can be monitored from the PBX Web UI under Status → Active Calls. This page displays all current call sessions in real time, including call state, involved extensions or trunks, and call duration.
Yes. For each extension, administrators can configure the maximum number of allowed call lines under Extensions → Features → Call Settings. This prevents a single extension from consuming excessive PBX call resources.
Concurrent call limits are enforced based on the active PBX license. When the licensed call limit is reached, additional calls will be rejected until an active call ends. These limits apply globally across all extensions and trunks.
GCC PBX uses inbound and outbound routing rules to control call flow. Inbound routes match incoming calls based on trunk or DID, while outbound routes determine which trunk is used for outgoing calls based on dial patterns and priority.
Codec preferences can be configured per extension under Extensions → Media. Administrators can prioritize or restrict codecs to control bandwidth usage and audio quality for specific users.
In the Extension→Features→Other Settings, you can specify which Music On Hold the extension uses when placing callers on hold.
Enabling SCA for an extension (under Extensions→Features→Other Settings) allows it to share its line state with other devices. When SCA is enabled, Concurrent Registrations can only be set to 1.
The Follow Me feature allows you to define a sequence of numbers (e.g., your desk phone, then your mobile) for incoming calls to try. The system will ring each number in your designated order until the call is answered or it reaches the final destination, like voicemail.
Call Privileges (Internal, Local, National, International) control which outbound routes a user can access. A user must have a privilege level equal to or higher than the level set on an outbound route to make calls using that route. For example, a user with “Local” privileges cannot use a route set to “National”.
Configuration, Provisioning & Firmware
PBX configuration backups can be generated from the PBX Web UI under Maintenance → Backup. Administrators can back up PBX settings, call records, voicemail, recordings, and other PBX-related data for recovery or migration purposes.
Yes. PBX backups created on GCC can be restored through the PBX Web UI. In addition, GCC PBX supports conversion and restoration of UCM63xx series PBX backups (firmware 1.0.27.x and above) using the backup conversion feature.
PBX firmware updates are delivered as part of the GCC system firmware. Updating the GCC device firmware will also update the embedded PBX module. It is recommended to back up the PBX configuration before performing any firmware upgrade.
GCC PBX supports template-based endpoint provisioning, but it does not expose this functionality under the name “Zero Config” as used on UCM series PBXs.
On GCC, endpoint provisioning is implemented through the UC Endpoints module (Device Management → VoIP Devices). The provisioning logic is the same as UCM Zero Config, but is structured as a dedicated module and integrated with GCC’s converged networking and PBX architecture.
Troubleshooting & Maintenance
If extensions fail to register with the GCC PBX, verify the following in order:
- Go to HOME→Overview→Device Modules and ensure the PBX module is enabled. If the PBX is disabled, extensions cannot register.
- Check the PBX IP shown in the Overview page and confirm the endpoint can reach it over the network. Ensure there are no routing, VLAN, or firewall rules blocking SIP traffic.
- Ensure the extension exists in the PBX and is correctly assigned to the endpoint. Verify the SIP username, authentication ID, and password match the extension configuration.
- If the endpoint is provisioned through the UC Endpoints / VoIP Devices module, make sure the device successfully downloaded its configuration file. After making changes, send a NOTIFY to force reprovisioning.
- Ensure the endpoint and PBX use compatible SIP transport (UDP, TCP, or TLS) and that the SIP port is correct. Mismatched transport settings will prevent registration.
- If the endpoint is behind NAT, verify NAT traversal settings and that the required ports are not blocked.
- Use the PBX network troubleshooting tools to identify authentication failures, unreachable servers, or rejected registrations. This is often the fastest way to pinpoint the root cause.
Enable TLS Key and/or SRTP debugging before capturing packets. GCC generates key logs with the capture. Import the SSL key log into Wireshark to decrypt SIP-TLS or SRTP streams.
Yes. GCC PBX supports Concurrent Multi-user Login. However, if two users try to modify the same configuration, the system will show a prompt.
You can use the built-in network tools under Maintenance→Network Troubleshooting.
- Use Ping to test basic connectivity.
- Use Traceroute to identify the network path and locate where a connection may be failing.
You can configure this under Maintenance→Syslog. Enter your remote syslog server’s IP address and select the specific modules and log levels you wish to forward.