This Frequently Asked Questions (FAQ) document provides concise answers and guidance for using Grandstream’s SoftwareUCM. It is intended to assist administrators and users in resolving common issues and understanding key features.
Product Overview & Specifications
SoftwareUCM is built on AlmaLinux, a stable enterprise-grade Linux distribution, and its telephony core is powered by Asterisk 16.
In addition, Grandstream integrates its own enhancements, including UI components, provisioning logic, media handling, security modules, and Wave communication services, to provide a complete PBX system beyond standard Asterisk capabilities.
There are three installation methods for SoftwareUCM:
- Bare-metal: Supports x86-based physical servers that meet SoftwareUCM’s CPU, memory, and storage requirements.
- Virtual Machine: Supports VMware Workstation (16.1.0+), Hyper-V (10.0.19041.1 +), KVM (4.5.0+), VMware ESXi (8.0), and VirtualBox (7.0+).
- AWS Cloud Deployment (EC2): SoftwareUCM can be deployed on Amazon Web Services using a virtual machine image exported from a supported hypervisor.
SoftwareUCM supports up to 10,000 extension users, 30,000 simultaneous SIP registrations, 2,500 concurrent calls, and 50 call attempts per second (CAPS).
These limits apply to a single instance and assume adequate CPU and memory resources. Performance may vary depending on call recording usage, call center functions, or video-related workloads. Refer to the SoftwareUCM Specifications and Server Requirements guide for recommended hardware specifications based on your expected deployment scale.
A single SoftwareUCM instance does not support multi-tenant functionality with data isolation.
Each SoftwareUCM instance needs to be assigned an independent IP address. Due to limitations such as multiple IP restrictions in cloud services and the lack of support for MAC-VLAN, cloud services like AWS and Google Cloud do not support multi-tenant mode.
SoftwareUCM integrates with Grandstream’s GDMS cloud platform for device provisioning, firmware upgrades, and configuration template deployment. It also supports local provisioning via Zero Config (for Grandstream phones), DHCP Option 66/43, and encrypted XML configuration files.
Yes. Starting firmware version 1.0.33.7, SoftwareUCM supports two HA modes:
- Local Hot Standby: two SoftwareUCM instances are deployed on the same site. A shared virtual cluster IP address ensures seamless switchover if the active instance fails.
- Remote Disaster Recovery: the primary and secondary instances are deployed at different physical locations. When the primary site becomes unavailable, the secondary automatically takes over.
Both modes synchronize configuration and call data in real time via the shared network interface. No dedicated physical heartbeat cable is required, unlike hardware UCM devices. Refer to the HA section of the SoftwareUCM User Manual for configuration details.
Supported voice codecs include Opus, G.711 A-law/U-law, G.722, G.726, G.729A/B, iLBC, and GSM.
Supported video codecs include H.264, H.263, H.263+, and VP8. Opus provides adaptive audio quality for low-bandwidth or unstable networks, while H.264 ensures broad device compatibility for video calls.
Supported languages include English, Simplified Chinese, Traditional Chinese, Spanish, French, Portuguese, German, Russian, Italian, Polish, Czech, and Turkish.
SoftwareUCM supports SIP over UDP/TCP/TLS, RTP/SRTP, DNS, DHCP, NTP, HTTPS, SSH, PPPoE, STUN/TURN/ICE, LDAP, IPv6, and OpenVPN. This ensures compatibility with a wide range of SIP endpoints, service providers, and network environments.
The maximum number of extensions and concurrent calls supported by SoftwareUCM is controlled by the license. To increase these limits, you can upgrade the license or purchase additional capacity add-ons.
SoftwareUCM also supports the 1+N Media Cluster feature, which expands media processing capacity by allowing a Business Server to work with up to 5 Media Servers. However, Media Servers do not increase the licensed extension or concurrent call limits and should not be confused with license-based capacity expansion.
The 1+N Media Cluster feature allows a SoftwareUCM Business Server to be paired with up to 5 Media Servers to handle higher media processing workloads. The business server manages all PBX functions, call control, and administration. The media servers handle media traffic only, with no PBX functionality of their own.
For more information on the SoftwareUCM Cluster feature, please refer to this guide.
Initialization & Licensing
On your first login, use the username “support“. You will be prompted to set a password, which will be required for all future logins.
Use the console → List SoftwareUCMs to view the IP, username, and password, then log in through a web browser.
To activate your SoftwareUCM free trial, follow these steps:
- After the initial installation, you will be prompted to Select SoftwareUCM Device Mode. Select PBX Mode and click Next to proceed. Selecting Media Server Mode will skip license activation entirely, as media servers do not require a license.
- Log into your SoftwareUCM account. You must read and agree to the SoftwareUCM License Agreement to proceed.
- Click on the Free trial link to go to the trial application page.
- Complete the trial application form with the necessary information.
- Access your email inbox to find a message containing the license file. Download this file from the attachment.
- Back in the SoftwareUCM interface, click the Upload button.
- Use the file browser to find and select the downloaded license file from your computer, then upload it.
Once the license file is successfully added, your trial will be activated. The confirmation page will show the activation and expiration dates for your trial, along with the details of your base package, which includes 100 user extensions and a maximum of 32 concurrent calls.
Before activation, you will be prompted to select the device operating mode:
- PBX Mode: requires license activation. Supports both online and offline activation for physical machines. Virtual machine deployments only support online activation.
- Media Server Mode: no license activation required. The device operates solely as a media server within a 1+N cluster and has no PBX functionality.
For PBX Mode activations, the following applies:
- Online activation requires the device to be connected to the internet to communicate with GDMS for license verification.
- Offline activation requires exporting the device information package and providing it to your reseller, who will supply a license file bound to that specific device.
Each license file can only be bound to one SoftwareUCM instance, and each instance can only be associated with one license file.
Switching from Media Server Mode to PBX Mode, or vice versa, requires a factory reset.
Deleting an instance will also permanently delete its associated license. The license cannot be recovered after deletion.
You can use the console to view and update the overall system network settings. To modify the network configuration for a specific instance, use the “Network Settings” option within the SoftwareUCM Management console menu.
It could be one of the reasons below:
- If you are using a virtual machine, it must be online for license verification. Otherwise, the license may become invalid.
- Cloning/Copy/Transfer virtual machine instances or similar behavior can cause the license to expire/invalid.
- If you are using a physical machine, replacing the machine’s hard drive can cause the license to become invalid.
- The license validity period has ended.
In physical machine installations, licenses are tied to hard disk information. As a result, changing it may invalidate the license. To ensure the SoftwareUCM installation will still work after a hardware replacement, make a data backup prior to the replacement. After replacing the hardware, contact Grandstream technical support through the HelpDesk (or with the assistance of your reseller) and submit the following details:
-The MAC address associated with the license (found in the purchase confirmation email)
-The old license file or order number (from your reseller), hardware information for the machine (exportable from the License Management page)
-A description of the situation.
The Grandstream technical support team will then complete the license verification and processing.
You can contact Grandstream technical support through the HelpDesk (or with the assistance of the reseller), and submit the detailed information to the Grandstream technical support team. Grandstream will complete the license verification and processing (generate a new License file/contact you for further instructions).
The information includes:
1. The MAC address associated with the license (found in the License Management page. If you cannot sign in SoftwareUCM, check the purchase confirmation email).
2. The old license file or order number (from your reseller).
3. If it’s a physical machine, provide the hardware information (exported from the License Management page).
4. Description of the situation.
For virtual machines, cloning or image copying will result in invalid licenses. If you need to replace the machine, ensure that both machines are not running simultaneously. Once the cloning is completed, the old environment must be discarded (power off or uninstall the machine) before the new machine is put into operation, and only the new environment should be kept running. For physical machines, if the license becomes invalid due to hardware replacement or upgrade, you must contact Grandstream for assistance in transferring the license.
Call Management & Advanced Features
Go to Web GUI→System Status→Active Calls. This page shows all active calls in real-time, their status (ringing, connected), and their duration. Calls are color-coded (grey, orange, red) to indicate their length and potential for being abnormal.
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.
Yes. In the Extensions→Features→Call Settings section, you can set “The Maximum Number of Call Lines” for the extension. A value of 0 indicates no limit. This prevents a single extension from using all available call paths.
This can be done through the “Alert-Info” setting in multiple locations (Features, Advanced Settings), you can trigger different ring patterns on supported phones:
- Pre-configured patterns (Ring1 through Ring10, bellcore patterns)
- Custom patterns defined in phone configurations
- Different patterns for different call types (internal/external)
In the Extension→Media tab, you can reorder and prioritize codecs for each extension. This allows you to force specific codecs for certain users (e.g., G.722 for HD voice quality).
In the Extension→Features→Other Settings, you can specify which Music On Hold the extension uses when placing callers on hold.
When enabled for an extension (under Extension→Features→CC Settings), the SoftwareUCM will automatically call back the extension when a previously busy or unavailable called party becomes free.
LDAP & Phonebook Management
In the extension’s settings under the Features→Other Settings tab, users can configure the “Enable LDAP” option to remove or include the extension in the SoftwareUCM LDAP phonebook.
Yes. When you configure a SIP Peer Trunk to another UCM, you can enable the “Sync LDAP Enable” option in the trunk’s advanced settings. This allows the two PBXs to automatically exchange and sync their local LDAP phonebooks, creating a unified directory.
You can directly export the LDAP phonebook in CSV, XLS, VCF, and XML format by navigating to System Settings→LDAP Server→LDAP Phonebook. On this page, you will find an “Export Selected Phonebook” button which allows you to download the directory entries.
Yes, any device or application that supports standard LDAP protocol can connect to the SoftwareUCM LDAP server. This includes phones from other manufacturers, email clients, CRM systems, and mobile applications that support LDAP directory integration.
No. The default PBX phonebook (ou=pbx,dc=pbx,dc=com) cannot be edited or deleted from the LDAP phonebook section. To edit the contacts, please update extension information under Extensions, and changes will sync automatically.
On the phone, configure:
- LDAP Server Address: [SoftwareUCM IP]
- Port: 389
- Base DN: dc=pbx,dc=com
- Username: cn=admin,dc=pbx,dc=com
- Password: [SoftwareUCM LDAP Root Password]
- LDAP Name Attributes: CallerIDName, Email, Department, FirstName, LastName, etc.
- LDAP Number Attributes: AccountNumber, MobileNumber, HomeNumber, etc.
You need to enable the global setting that allows LDAP contacts to appear in Wave. Navigate to System Settings→LDAP Server→LDAP Phonebook→LDAP Settings and ensure “Display LDAP Contacts on Wave” is enabled.
Configuration, Provisioning, & Firmware
Encrypted XML configurations use AES encryption, TLS protects configuration file transfers, and device authentication prevents unauthorized phones from registering.
Verify the device is powered on and connected to the same network segment. Try different scan methods, as some network configurations may block PING but allow ARP or SIP NOTIFY discovery. Also check firewall settings that might prevent discovery protocols.
This happens due to SoftwareUCM’s three-layer configuration priority system. Even though you set a parameter in the Global Policy (Layer 1), it can be overridden by settings in Model Templates (Layer 2) or Device-specific configurations (Layer 3).
In Global Policy→Localization, configure NTP settings to point to your SoftwareUCM’s IP address. Set the NTP update interval and time zone. This ensures all provisioned phones maintain consistent time settings across your organization.
The model template package for that device series isn’t installed. Go to Device Management → Zero Config → Model Update to view and install available template packages.
Some devices require manual package installation. If your model still doesn’t appear after installation, contact Grandstream support to check for template availability.
This is usually caused by one of the following issues:
- Incorrect Filename: The firmware file must exactly match the specific name your device model is looking for. (Example: For a DP755 base station, it must be dp755fw.bin)
- Wrong Template Assignment: The firmware setting is configured in a template that is not being applied to the device, or a higher-priority template is overriding it.
- Conflicting Firmware Source: A different template (like a Model Template) might be set to use a URL-based firmware server instead of the “UCM Server.”
Troubleshooting & Maintenance
This means the SoftwareUCM instance did not get assigned an IP address. You need to check your network settings, such as DHCP or static IP configuration, to resolve this.
You can troubleshoot extension registration issues by following these steps:
- Check Extension Status: Verify the registration state of the extension in SoftwareUCM.
- Test Network Connectivity: Make sure the endpoint can reach SoftwareUCM over the network.
- Verify SIP Credentials: Ensure the username, password, and authentication settings on the endpoint match those configured in SoftwareUCM.
- Check Network and Firewall Settings: Confirm that firewall rules are not blocking SIP traffic. Also, check whether SoftwareUCM’s Fail2Ban has automatically blocked the endpoint IP due to repeated failed registration attempts.
- Review System Events: Look for SIP registration failure alerts in the System Events log.
- Verify PBX Settings: Confirm that the SIP port and transport protocol configured on SoftwareUCM match the settings on the endpoint.
Email failures are typically caused by:
- Incorrect SMTP host, port, encryption type, or authentication
- The SMTP server is blocking unknown sender addresses
- Firewall blocking outbound SMTP traffic
- Using unverified or restricted email accounts
Testing email delivery in System Settings → Email Settings helps diagnose configuration errors.
GDMS limits packet captures to 5 minutes maximum. Captures stop automatically at the 5-minute mark or sooner if manually stopped.
Only alerts marked with the GDMS sync icon in SoftwareUCM→System Events→Alert Events List can be synced. Additionally, “Alert Events Sync” must be enabled under RemoteConnect→Plan Settings.
GDMS only allows one active diagnostic task at a time. If a test is already running (Ping, Traceroute, Syslog, Capture Trace, etc.), you must wait for it to finish or stop it before launching another.
Enable TLS Key and/or SRTP debugging before capturing packets. SoftwareUCM generates key logs with the capture. Import the SSL key log into Wireshark to decrypt SIP-TLS or SRTP streams.
Network & Security
Enable SRTP or ZRTP for the SoftwareUM extension under the Media tab, and ensure the endpoint supports the chosen protocol. Both encrypt RTP packets, protecting audio from network eavesdropping.
Enable TLS transport under SIP Settings → TCP/TLS and upload valid TLS certificates. TLS encrypts signaling between phones and the PBX, preventing SIP message interception. Devices must also be configured for TLS and trust the PBX certificate.
Yes. Use Fail2Ban under System Settings→Security→Fail2Ban. It automatically detects and blocks IP addresses after multiple failed authentication attempts.
Enable HTTPS with valid certificates, enforce strong passwords, configure login attempt limits with lockouts, restrict access by IP range, and enable two-factor authentication.
Yes, IPv6 support was introduced in 1.0.32.7. IPv6 can be configured independently of IPv4 and is available regardless of the selected network interface mode (single or dual NIC).
IPv6 can be configured under System Settings → Network Settings → Basic Settings → IPv6 Address. In dual NIC mode, IPv6 is configured separately for each interface (LAN 1 and LAN 2).
Alternatively, users can configure IPv6 from the console Network Settings for each interface.
Yes, dual NIC support is supported starting firmware 1.0.32.7. When enabled, both LAN 1 and LAN 2 can be active simultaneously, each assigned to a different subnet. This is useful for separating SIP signaling and media traffic, or for connecting the SoftwareUCM to two distinct network segments.
To use dual NIC mode:
- Enable it first from the SoftwareUCM console Network Settings.
- Once enabled, the Network Settings page in the web UI will update to display separate configuration sections for LAN 1 and LAN 2 under both the IPv4 and IPv6 tabs.
- LAN 1 and LAN 2 must be assigned IP addresses on different subnets.