Grandstream UCM IP PBX systems ship with generic hold music. This guide shows you how to replace it with AI-generated promotional audio from HoldCast — in under 10 minutes, no IT ticket required.
Every Grandstream UCM ships with a default music-on-hold library — generic tracks that loop indefinitely while your customers wait. It doesn't promote your business. It doesn't explain your services. It just fills silence.
What HoldCast does instead: AI writes a custom script based on your business, a professional voice reads it, background music is mixed in, and you download a finished audio file ready to upload to your UCM. Your callers hear your promotions, not someone else's royalty-free jazz.
The ROI is immediate. If your on-hold message mentions a seasonal special, an upsell service, or your website — and even one caller acts on it per week — the message paid for itself. Grandstream UCM handles hundreds of concurrent calls across its supported models. Every caller in queue is an audience.
HoldCast audio files work with the entire Grandstream UCM product line. All models share the same web-based admin interface and Music on Hold upload workflow.
UCM6102, UCM6104, UCM6108, UCM6116. Entry-level SMB PBX. Supports WAV and MP3 for Music on Hold.
✓ COMPATIBLEUCM6202, UCM6204, UCM6208. Mid-range PBX with advanced queue management. Full MOH upload support.
✓ COMPATIBLEUCM6301, UCM6302, UCM6304, UCM6308. Enterprise-grade. Multiple MOH categories with per-queue assignment.
✓ COMPATIBLEHigh-density PBX and UCM RemoteConnect cloud deployments. Same admin interface, same upload process.
✓ COMPATIBLEGrandstream UCM systems accept WAV and MP3 for Music on Hold. HoldCast generates both. For best UCM compatibility, download WAV.
| Format | UCM Support | HoldCast Output | Recommendation |
|---|---|---|---|
| WAV (PCM 16-bit) | ✓ Full | ✓ Yes | Best choice for UCM |
| MP3 | ✓ Supported | ✓ Yes | Works on most UCM firmware versions |
| WAV (G.711 µ-law) | ✓ Full | Convert from PCM | Required only on older UCM6100 firmware |
UCM6100 units running firmware below 1.0.20 may require G.711 WAV encoding. If your file doesn't play, download the WAV from HoldCast and convert using a free tool like Audacity (File → Export → WAV, 8kHz, Mono, µ-law). UCM6200 and UCM6300 on current firmware accept standard 44.1kHz WAV without conversion.
This guide covers both the legacy admin UI and the newer Grandstream UCM web interface (firmware 1.0.20+). The steps are nearly identical across all UCM models.
Visit holdcast.polsia.app/create.html. No account required to start.
Enter your business name, industry, key services, and anything you want to promote right now — a seasonal special, a new service, website URL, or hours of operation.
Select a professional AI voice and optional background music style. A warm, upbeat tone works well across most business types.
HoldCast writes the script and produces the finished audio file. Preview it in your browser and make edits if needed.
Click the WAV download button. Save the file — you'll upload this directly to your Grandstream UCM admin portal.
Open a browser and navigate to your UCM's IP address (typically http://192.168.x.x:8088 or the UCM's hostname). Log in with admin credentials.
In the left sidebar, go to:
On older UCM6100 firmware this may appear under Advanced Settings → Music On Hold.
Click Add to create a new Music on Hold category. Give it a descriptive name like HoldCast-PromoSpring2026. This keeps your custom audio separate from the default library so you can swap it seasonally.
In the new MOH category, click Upload Audio File (or the upload icon) and select the WAV file you downloaded from HoldCast. The file will appear in the category's audio list once uploaded.
Click Save then Apply Changes (the orange bar at the top of the page) to push the configuration live. Your new MOH category is now active.
Navigate to the queue or extension you want to update:
Select your new HoldCast MOH category from the dropdown. Save and Apply Changes again. Test by calling in and placing yourself on hold.
Create a separate MOH category for each season or promotion. Name them clearly (e.g., HC-Summer2026, HC-Holiday2026). When it's time to update, upload the new HoldCast file to a new category and swap the queue assignment — zero downtime, instant rollback if needed.
Generic hold music signals nothing. A custom on-hold message signals professionalism — and it sells.
Promote your current offers. Running a summer special? New service launch? Your callers are a captive audience. A 2-minute on-hold message can mention your promotion three times during an average hold session.
Reduce hang-ups. Silence and generic music cause callers to hang up within 40–60 seconds on average. Voice content — even informational content — dramatically extends hold tolerance because the caller feels engaged.
Direct callers to your digital channels. Mentioning your website, booking portal, or self-service options during hold reduces call volume over time. Common: "Did you know you can book online at [your site]? Someone will be with you shortly."
Seasonal updates cost you 3 minutes. Traditional on-hold services charge $39–$75/month and require scheduling a recording session days in advance. HoldCast generates a new file in under 3 minutes — update your Grandstream UCM as often as you run promotions.
Create a professional, promotional on-hold message in 3 minutes. Download as WAV, upload to your UCM — done.
🎤 Generate Free On-Hold Message →AI-powered · WAV & MP3 download · Works with all Grandstream UCM series · No account required to start