> ## Documentation Index
> Fetch the complete documentation index at: https://doc.khcolo.com/llms.txt
> Use this file to discover all available pages before exploring further.

# GSM/VoIP Gateways for 3CX and Cambodian Mobile Networks

> Bridge mobile GSM networks to your 3CX phone system with KHCOLO's UC2000-VF gateway — enabling local call termination and bulk SMS from one device.

Cambodia's mobile-first telecommunications landscape means that a significant share of business calls land on GSM networks rather than fixed lines. KHCOLO's GSM/VoIP gateway solutions let you route those calls intelligently through your 3CX phone system, slashing mobile termination costs, enabling bulk SMS campaigns, and giving your team a single unified communications hub that spans both VoIP and cellular networks.

## UC2000-VF 16-Channel GSM/3G/4G Gateway

The **UC2000-VF** is a rack-mountable, carrier-grade gateway that bridges up to 16 simultaneous GSM, 3G, or 4G channels into your SIP-based 3CX environment. Designed for businesses with moderate-to-high outbound call volumes or SMS requirements, it eliminates the need to purchase separate SIM-based devices for each mobile operator you work with.

### Hardware Specifications at a Glance

| Specification       | UC2000-VF Detail                            |
| ------------------- | ------------------------------------------- |
| **Channels**        | 16 simultaneous voice/SMS channels          |
| **Network support** | GSM (2G), 3G (WCDMA/HSPA+), 4G LTE, VoLTE   |
| **SIM slots**       | 16 (one per channel, hot-swappable)         |
| **SIP protocol**    | SIP/2.0 — registers as a trunk on 3CX       |
| **SMS API**         | HTTP/HTTPS REST API for automated messaging |
| **Form factor**     | 1U rack-mount                               |
| **Power**           | Redundant PSU option available              |

<Note>
  **VoLTE and Hot-Swappable SIM Modules:** The UC2000-VF supports **VoLTE (Voice over LTE)**, delivering HD voice quality over 4G networks — important as Cambodian carriers continue phasing out 2G infrastructure. Each of the 16 SIM slots is **hot-swappable**, meaning you can insert, remove, or swap SIM cards without rebooting the device or interrupting active channels. This makes operator changes and SIM rotation for anti-blocking policies completely seamless in production environments.
</Note>

***

## Use Cases

### 1. Bridging Mobile GSM Networks to 3CX

Connect the UC2000-VF to your 3CX phone system as a SIP trunk. Inbound calls from any Cambodian mobile number ring directly to 3CX extensions, queues, or IVR menus — just like calls from a fixed SIP provider. Outbound calls to mobile numbers are routed through the gateway's local SIM cards, using domestic mobile rates instead of expensive international VoIP termination fees.

<Steps>
  <Step title="Insert SIM Cards">
    Load SIM cards from your preferred Cambodian operators (Cellcard, Smart, Metfone, or others) into the hot-swappable slots. Mix operators across slots for redundancy and least-cost routing.
  </Step>

  <Step title="Register as a 3CX SIP Trunk">
    Configure the UC2000-VF's IP address, SIP credentials, and codec settings in the 3CX Management Console under **SIP Trunks**. The gateway registers like any standard SIP provider.
  </Step>

  <Step title="Configure Outbound Routing Rules">
    In 3CX, create outbound rules that send calls prefixed with Cambodian mobile codes (e.g., 01x, 07x, 08x, 09x, 096–099) through the gateway trunk for least-cost routing.
  </Step>

  <Step title="Test and Monitor">
    Place test calls across each channel. Use the UC2000-VF's web management interface and 3CX call logs to verify connectivity, audio quality, and channel availability.
  </Step>
</Steps>

### 2. Local Mobile Call Termination

For businesses that need to present a local Cambodian mobile CLI (Caller Line Identification) when dialling customers, the UC2000-VF ensures your outbound calls appear as familiar local numbers rather than international VoIP DIDs. This dramatically improves answer rates — particularly important for sales and customer service teams.

<Info>
  Local SIM-based termination can reduce outbound call costs to Cambodian mobile numbers by up to 60–80% compared to international VoIP routes, depending on your current provider's mobile termination rates.
</Info>

### 3. Bulk SMS Sending via Automated API

The UC2000-VF exposes an **HTTP/HTTPS REST SMS API** that your applications can call directly to send outbound SMS messages through any of the installed SIM channels. Common use cases include:

* **Appointment reminders** — automatically triggered from your CRM or scheduling system
* **OTP / two-factor authentication** — send one-time passcodes to customers via local SMS
* **Marketing campaigns** — bulk promotions distributed through multiple SIM channels simultaneously
* **Transactional alerts** — order confirmations, payment receipts, and delivery notifications

***

## Full Feature List

<CardGroup cols={2}>
  <Card title="16 Simultaneous Channels" icon="layer-group">
    Handle up to 16 concurrent voice calls or SMS streams — scale to multiple units for higher capacity.
  </Card>

  <Card title="Multi-Network SIM Support" icon="sim-card">
    Insert SIM cards from any Cambodian mobile operator. Mix networks across slots for redundancy.
  </Card>

  <Card title="VoLTE HD Voice" icon="phone-volume">
    Crystal-clear HD audio over 4G LTE networks, future-proofing your setup as 2G is phased out.
  </Card>

  <Card title="Hot-Swappable SIMs" icon="arrows-rotate">
    Replace or rotate SIM cards live without rebooting or dropping active calls on other channels.
  </Card>

  <Card title="REST SMS API" icon="code">
    Integrate SMS sending directly into your web apps, CRM, or ERP via a simple HTTP/HTTPS API.
  </Card>

  <Card title="3CX SIP Trunk Integration" icon="plug">
    Registers natively as a SIP/2.0 trunk in 3CX — no special drivers or middleware required.
  </Card>

  <Card title="Web Management Console" icon="display">
    Monitor channel status, SIM signal strength, call statistics, and SMS logs through a browser-based dashboard.
  </Card>

  <Card title="Least-Cost Routing" icon="route">
    Work with 3CX's outbound routing rules to automatically select the lowest-cost SIM for each call destination.
  </Card>
</CardGroup>

***

## Integration with 3CX

The UC2000-VF pairs directly with KHCOLO's [3CX phone system deployments](/3cx/overview). Once registered as a SIP trunk, it participates fully in 3CX features:

* **Ring groups and call queues** — inbound mobile calls join the same queues as VoIP calls
* **IVR menus** — callers dialling your mobile number hear the same auto-attendant as any other caller
* **Call recording** — mobile calls are recorded alongside VoIP calls in the 3CX recording library
* **Reporting** — mobile call data appears in 3CX real-time dashboards and call log reports
* **Failover** — if the gateway is unreachable, 3CX can automatically fall back to an alternative SIP trunk

<Tip>
  For maximum resilience, KHCOLO recommends loading SIM cards from at least two different Cambodian mobile operators across your 16 channels. If one operator experiences a network outage, 3CX's outbound routing rules will automatically prefer channels on the working operator.
</Tip>

***

## Getting a Gateway Deployed

Contact the KHCOLO team to discuss your call volume, SMS requirements, and preferred mobile operators. We handle procurement, rack installation, SIM configuration, and full 3CX trunk integration — so your gateway is live and routing calls from day one.