GSM Gateway for EPABX: Use a SIM Card as an Outside Line

Short answer: a GSM gateway is a small box that takes a mobile SIM card and turns it into an ordinary telephone line. You plug that line into the LINE (CO) port of your EPABX, and every extension can then make and receive outside calls through the SIM, with no landline connection needed. On our store the CCL FCT-GSM-DU single-SIM gateway costs ₹3,299, and a complete starter setup with a 4-extension exchange starts at ₹5,698. Prices include GST and delivery across India is free.

What is a GSM gateway for an EPABX?

An EPABX shares outside lines between many internal phones. Traditionally those outside lines were copper landlines from BSNL or a private operator. Many shops, farmhouses, godowns and new offices in India no longer have a landline, or the landline takes weeks to install. A GSM gateway fills that gap. It behaves like a mobile phone without a screen: it registers the SIM on the mobile network, and on the other side it gives out a standard two-wire telephone line, exactly what an EPABX LINE port or a single desk phone expects.

The CCL FCT-GSM-DU listing describes it in those terms: it generates a normal telephone line from a GSM SIM and can be connected to a PBX. People also call this kind of device an FCT (fixed cellular terminal) or a fixed wireless terminal.

How does it work with the exchange?

1. The SIM sits inside the gateway, and the gateway's antenna picks up the mobile signal.
2. The gateway's line output connects to a LINE or CO port on the EPABX, using the same telephone cable a landline would use.
3. When a customer calls the SIM number, the gateway rings the EPABX line, and the exchange rings the extensions you have programmed for incoming calls, often just reception.
4. When staff dial out, they pick the outside line (usually by dialling 0 or 9, depending on how the exchange is set up) and the call goes out through the SIM.
5. Internal calls between extensions never touch the SIM. They stay free, as they always are on an EPABX.

For the FCT-GSM-DU, the listing adds two useful details. It does STD code addition, so staff can dial a local landline number without the area code. And it does caller ID generation, so the incoming mobile number is passed on. To see that number on a desk phone, the exchange must support caller ID and the phone needs a display, such as the Beetel C51. It also has a signal strength indicator, which helps when you choose where to mount it.

Which SIM cards work?

The FCT-GSM-DU listing says it works with all 2G, 3G and 4G SIMs except Jio. Jio carries voice only over 4G VoLTE, which this type of gateway does not use. In practice that means an Airtel, Vi or BSNL SIM. Use a plan with enough calling for your business, and turn off any SIM lock PIN before inserting the card, or the gateway cannot start it.

Where should you fit the GSM gateway?

• Where the signal is strong. The listing's install steps say to place it where mobile signal is good. Check the signal strength indicator before you fix it to the wall.
• Not inside a steel cabinet or basement. Metal and concrete cut mobile signal. A spot near a window or on an upper floor often works better.
• Near the exchange if possible. If the best signal is far away, mount the gateway there and run telephone cable back to the EPABX LINE port, just as you would for a landline. See how an EPABX is wired for cable and termination.
• Near a power socket. The gateway needs power to stay on the network. If your exchange is on an inverter or UPS, put the gateway on the same backup so outside calls keep working in a power cut.

How to set it up

1. Insert the SIM (with PIN lock removed) and connect the antenna.
2. Power on and check the signal indicator. Move the unit if the signal is weak.
3. Connect the gateway's line output to LINE 1 on the EPABX with telephone cable.
4. Call the SIM number from another mobile and check that the extensions ring as programmed.
5. Dial out from an extension to a mobile and to a local landline to confirm both work.

GSM gateway, FXO gateway or landline: which do you need?

These get mixed up because all three sit on the outside-line side of a phone system.

• GSM gateway: a SIM becomes an outside line for a normal EPABX. Choose it when you have no landline, or want a mobile number on your reception phones.
• FXO gateway: brings existing landlines into an IP-PBX that runs on your computer network. It does not take a SIM. Our IP-PBX vs EPABX guide explains FXO and FXS.
• Landline: still the simplest if you already have one. It plugs straight into the LINE port with no extra box.

Many businesses use both: one landline on LINE 1 and a GSM gateway on LINE 2. That needs an exchange with at least two line ports, such as a CCL 206B or 308B.

Gateway and matching exchanges on our store

Product	Lines / extensions or key spec	Role in a SIM-based setup	Price
CCL FCT-GSM-DU	Single SIM; 2G/3G/4G except Jio; caller ID generation	Turns the SIM into a telephone line	₹3,299
CCL 104B	1 line / 4 extensions	Small shop or clinic on one SIM	₹2,399
CCL 108 (welcome message)	1 line / 8 extensions; internal and trunk caller ID	8 desks; greets callers on the SIM number	₹3,799
CCL 206B	2 lines / 6 extensions	Landline plus SIM, or two SIMs	₹4,400
CCL 308B	3 lines / 8 extensions	Busy front desk with mixed lines	₹4,900
Beetel C51	Corded phone with caller ID screen	Shows the incoming mobile number	₹999

Example budgets

• Shop with 4 phones, no landline: FCT-GSM-DU ₹3,299 + CCL 104B ₹2,399 = ₹5,698 (phones extra).
• Same, with two caller-ID phones in the box: FCT-GSM-DU ₹3,299 + Combo-CN143 (CCL 104B with 2 Beetel C51) ₹4,399 = ₹7,698.
• Office with 8 desks and a welcome message on the SIM line: FCT-GSM-DU ₹3,299 + CCL 108 ₹3,799 = ₹7,098.
• Two SIM lines for 6 desks: 2 × FCT-GSM-DU ₹6,598 + CCL 206B ₹4,400 = ₹10,998.

The FCT-GSM-DU had only a few units in stock on the date below, so for two or more pieces, message us on WhatsApp first. See all exchanges in EPABX systems, ready kits in intercom and telephone combos, and gateways in EPABX gateways and accessories.

FAQ

Can I connect a SIM card to an EPABX?

Not directly. You need a GSM gateway, which holds the SIM and gives out a normal telephone line that plugs into the EPABX LINE port.

Does the GSM gateway work with a Jio SIM?

The CCL FCT-GSM-DU listing says it works with 2G, 3G and 4G SIMs except Jio. Use an Airtel, Vi or BSNL SIM instead.

Will callers see my SIM number when I call from an extension?

Yes. Outgoing calls through the gateway go out on the SIM, so the person you call sees that mobile number.

Can I use a GSM gateway with a single phone and no EPABX?

Yes. The gateway's line output can go straight to one ordinary landline phone, which then works like a desk phone on a mobile number.

How many SIM lines can one EPABX take?

One per LINE port, with one single-SIM gateway per SIM. A CCL 206B takes two outside lines, a 308B three and a 416 four.

Do internal calls use SIM balance?

No. Calls between extensions stay inside the EPABX and are free. Only outside calls go through the SIM.

Prices are NavKar Systems website prices on 27 October 2026, inclusive of GST, and may change.