Phone Says “No Service” or Cannot Make Calls

If your phone displays “No Service” or you cannot place calls, the cause is usually a network or registration issue. The quick checks below resolve the problem most of the time. Work through them in order.

Quick Troubleshooting Checklist

1. Verify the internet works. Confirm other devices on the same network can browse normally. If nothing has internet, the problem is upstream of your phone.
2. Check the cable goes to the right port. The network cable from your wall or switch must plug into the Internet port on the back of the phone — not the PC port. The PC port is only for chaining a computer through the phone.
3. Reboot the phone. Unplug it for 5 seconds and plug it back in. If the phone uses an AC adapter, unplug the adapter; if it is powered over Ethernet (PoE), unplug the network cable for 5 seconds and reconnect.
4. Reboot the router. Some routers fall into a “partially working” state after long uptime or a power outage — some devices keep internet, others lose it. A 30-second reboot of the router often clears this. (If you are not comfortable doing this, skip ahead.)
5. Contact EMAK Telecom support if the issue persists.
6. Last resort: for a Yealink phone, a factory reset can clear stuck state. Confirm with support before doing this — a factory reset wipes any local personalization.

If This Is a New Installation

“No Service” right after install almost always points to a firewall or router blocking the SIP traffic the phone needs to register. Make sure your network allows the EMAK Telecom domains, IP ranges, and ports — see EMAK Telecom Ports and IPs to Whitelist. Pay particular attention to:

• SIP ALG — disable it on the router.
• Deep-packet-inspection rules that target SIP or UDP traffic.
• Restricted firewall profiles common in clinics and managed networks (SonicWall, NET+ ACDQ, etc.).

No Service FAQ

Other phones in the office work — only mine doesn’t.

That points to the individual phone or its cable. Try a known-good network cable, or swap your phone with another working one in the office to isolate which side is at fault.

The phone shows the right caller ID and registers, but outbound calls fail.

The registration is fine but call routing is the issue — usually a permission problem (some plans block long-distance) or a destination block. Contact EMAK Telecom support.

“No Service” only happens at certain times of day.

This is often a clue that your internet connection is being saturated. Heavy uploads or backups can starve the SIP keepalive traffic and cause registrations to time out. See improve VoIP call quality for QoS guidance.

The phone says “Not Registered” specifically.

Same root causes — the phone cannot reach EMAK Telecom’s SIP servers. Run through the checklist above; “Not Registered” and “No Service” are usually fixed the same way.

I unplugged everything and still no service after replug.

Give the phone a full minute to provision after re-plugging — it has to fetch configuration before registering. If it still fails, contact support and have your extension number handy.