How does FMC work?
The FMC technology connects a mobile phone to the SIP PBX (the SIP protocol ensures voice transmission over the internet) via an application or at SIM card level. The employee's mobile number is assigned as an extension of the PBX, and from that moment on, the same rules apply to the mobile as to the desktop IP telephone.
There are two basic approaches:
- Mobile app - The employee installs a softphone (software phone) and calls via mobile data or Wi-Fi. The call routes through the PBX, and the customer sees the company number, not the employee's personal mobile number.
- SIM-based FMC - The operator connects the SIM card directly to the SIP PBX at network level. The mobile phone functions as an extension even during standard mobile calls, with no special app required.
What will FMC bring to your company?
The main advantage of FMC is a unified identity: the customer always sees the company number, whether calling or receiving a call from an employee in the office, in a vehicle, or at home. The company does not need to maintain two separate communication structures: a fixed PBX for the office and mobile phones for field work.
- Field staff are reachable on the company line, not just on their personal mobile numbers.
- Call transfer from a mobile phone to a colleague works the same way as from an office telephone.
- Unanswered calls go to a shared queue or the company voicemail, not to personal mobile voicemail.
- Time rules and redirects also apply to mobile branches.
- Call records are consistent regardless of the device from which the employee made the call.
What to watch out for when installing an FMC?
The key parameter is connection quality. If an employee calls via the app in an area with weak signal, call drops or reduced audio quality may occur. It is therefore advisable to check the codec settings (voice compression method) and QoS (Quality of Service, i.e., prioritisation of voice traffic on the network).
Each mobile user typically requires their own extension licence in the central system. Security is also crucial, voice traffic should be encrypted to prevent potential eavesdropping. On virtualni-ustredna.cz you can add mobile extensions directly via the admin interface without complex network rule configuration.
Frequently Asked Questions
Does an employee need a new mobile number for FMC?
No. FMC adds a business extension to an existing mobile device. Customers call the company number, which is forwarded to the employee's mobile. The employee's personal mobile number remains unchanged.
Does FMC work without an internet connection?
The FMC application version requires a data connection (mobile data or Wi-Fi). The SIM-based FMC variant, implemented via the operator at the network level, operates over the mobile network even without a separate internet connection.
Is an FMC the same as a GSM gateway?
No. A GSM gateway is a hardware device that converts mobile network signals to VoIP. FMC is a broader term referring to the integration of mobile and fixed-line telephony at the PBX level, without requiring additional hardware on the customer's side.