IP Phones Not Making Calls? How Boardtac Solutions Restored a Business VoIP Telephone System in Kilimani, Nairobi

When office IP phones suddenly stop making internal or external calls, communication can quickly become difficult. Employees may be unable to reach colleagues, customers may experience delays, and normal business operations can be affected.

Although the problem may appear to be a faulty IP phone, the actual cause may be related to the VoIP telephone system, IP PBX configuration, GSM gateway, call-routing settings, SIP registration, or network connectivity.

In July 2026, Boardtac Solutions responded to a service request from a business in Kilimani, Nairobi, where the office telephone system was experiencing both internal and external calling problems. External calls through the GSM gateway were not working correctly, while one affected IP phone could not make internal extension calls.

What initially appeared to be a simple IP phone issue required a systematic assessment of the wider business communication system.

Quick Answer: Why Are IP Phones Not Making Calls?

An IP phone may fail to make calls because of incorrect PBX settings, failed SIP registration, extension configuration problems, GSM gateway routing errors, network connectivity issues, or changes to the telephone system.

The phone itself may still be functional. Proper troubleshooting helps identify the actual source of the problem and can restore communication without unnecessary equipment replacement.

The Customer’s Challenge

The customer relied on a business VoIP telephone system for daily communication. Office users operated IP phones connected to an IP PBX, while a GSM gateway supported outbound calling through the mobile network.

The reported problems included:

Office extensions could not make external calls through the GSM gateway.
One IP phone could not communicate with other internal extensions.
Daily communication between employees and external contacts was affected.
It was unclear whether the problem was caused by the IP phone, the PBX, the GSM gateway, or the office network.

Because several components work together in a business telephone system, replacing the affected phone without proper diagnosis could have failed to solve the underlying problem.

Our Technical Assessment

Boardtac Solutions carried out a structured assessment of the telephone system before recommending any equipment replacement.

The technical checks included:

Verifying the GSM gateway configuration.
Reviewing IP PBX extension settings.
Checking the connection between office extensions and the GSM gateway.
Examining outbound call-routing configuration.
Testing internal extension-to-extension communication.
Checking the affected IP phone configuration.
Verifying communication between the IP phone and the IP PBX.
Testing internal and external calling services.
Confirming that the relevant telephone system components were communicating correctly.

The assessment focused on identifying the actual cause of the communication failure rather than assuming that the IP phone hardware was defective.

The Solution

After identifying the configuration and communication issues affecting the system, our technical team completed the required corrective work.

The service included:

Reconfiguring the GSM gateway.
Restoring external calling services.
Reconnecting and configuring office extensions to use the appropriate GSM gateway routes for outbound calls.
Reconfiguring the affected IP phone.
Restoring internal extension-to-extension communication.
Testing internal calls between office users.
Testing external calling through the GSM gateway.
Verifying that the restored services were operating correctly.
Completing final system testing and commissioning.

Following the reconfiguration and testing process, the affected office telephone services were restored without unnecessary replacement of the existing equipment.

Why IP Phones May Stop Making Calls

An IP phone is only one part of a larger communication system. A problem affecting the PBX, network, gateway, extension settings, or call-routing configuration can prevent calls even when the phone itself is operational.

Common causes may include:

Incorrect IP PBX configuration.
SIP registration problems.
Incorrect extension settings.
GSM gateway configuration errors.
Outbound call-routing problems.
Network connectivity issues.
Changes to telephone system settings.
Power interruptions affecting communication equipment.
Incorrect gateway or trunk assignments.
Configuration inconsistencies following system changes.
Communication problems between the IP phone and PBX.

Professional diagnosis helps determine which part of the system is responsible before equipment is replaced.

Common Signs Your Office Telephone System Needs Attention

Your business may require professional VoIP support if you experience any of the following:

IP phones cannot make external calls.
Internal extension calls are failing.
One office phone cannot call other extensions.
Calls are not routing through the GSM gateway.
An IP phone displays a registration error.
Office extensions become unreachable.
Calls disconnect unexpectedly.
Voice quality becomes poor or unstable.
Calls take too long to connect.
Telephone services fail after a network change.
Calling problems begin after a power interruption.
Some phones work while others cannot make or receive calls.

Early diagnosis can reduce communication downtime and help prevent unnecessary replacement costs.

Why Professional VoIP Troubleshooting Matters

A business telephone system may include IP phones, an IP PBX, GSM gateways, SIP services, network switches, routers, and other communication components. These systems must be configured correctly and work together reliably.

A fault in one configuration area can affect multiple users or prevent specific services from working.

Professional troubleshooting can help identify issues involving:

IP phone configuration.
IP PBX programming.
Extension setup.
SIP registration.
GSM gateway configuration.
Outbound call routing.
Internal extension communication.
SIP trunk connectivity.
Office network connectivity.
Voice communication performance.
Business telephone system maintenance.

A systematic approach helps restore services while avoiding unnecessary changes or equipment replacement.

IP Phone Repair, Configuration and VoIP Support in Kenya

Boardtac Solutions provides professional business communication solutions for organisations that require reliable internal and external telephone services.

Our services include:

IP phone installation and configuration.
IP phone troubleshooting and support.
VoIP telephone system installation.
VoIP system troubleshooting.
IP PBX configuration and maintenance.
Yeastar PBX configuration and support.
GSM gateway installation and troubleshooting.
Extension programming and configuration.
SIP trunk configuration.
Business telephone system maintenance.
Office communication system upgrades.
Network infrastructure support for VoIP systems.
Remote and on-site technical support.

Whether your organisation operates a small office with a few extensions or a larger communication system with multiple users, Boardtac Solutions provides practical support based on the requirements of the existing system.

Frequently Asked Questions

Why is my IP phone not making calls?

The cause may be related to SIP registration, extension settings, PBX configuration, network connectivity, call routing, or gateway configuration. The IP phone may not necessarily be faulty.

Why can my IP phone make internal calls but not external calls?

If internal calls work but external calls fail, the issue may be related to outbound call routing, a GSM gateway, a SIP trunk, or the configuration that connects office extensions to external calling services.

Why can my IP phone make external calls but not internal calls?

The issue may involve the extension configuration, internal call-routing settings, PBX programming, or communication between the phone and the IP PBX.

Can a GSM gateway cause office phones to fail to make external calls?

Yes. If the GSM gateway configuration, connection, routing, or extension assignment is incorrect, office users may be unable to place external calls through the gateway.

Does an IP phone problem always mean that the phone is faulty?

No. Many calling problems originate from the PBX, network, gateway, extension settings, SIP registration, or call-routing configuration rather than the phone hardware.

Can a VoIP telephone system be restored without replacing equipment?

In some cases, yes. If the problem is caused by configuration or communication issues, professional troubleshooting and reconfiguration may restore the existing system without replacing the affected equipment.

Do you provide IP phone and VoIP support in Kenya?

Yes. Boardtac Solutions provides IP phone configuration, VoIP troubleshooting, PBX support, GSM gateway services, telephone system maintenance, and related business communication solutions in Nairobi and across Kenya.

About Boardtac Solutions

Boardtac Solutions provides professional ICT, business communication, networking, and security system solutions in Kenya.

Our technical services include IP phone installation, VoIP telephone systems, IP PBX support, GSM gateway configuration, structured network infrastructure, CCTV systems, access control solutions, IT support, system troubleshooting, maintenance, and technical services.

Our approach is to assess the existing system, identify the source of the problem, apply the appropriate solution, and verify operation before completing the service.

Need Help with Your IP Phones or Office Telephone System?

If your IP phones are not making calls, office extensions cannot communicate, external calls are failing, or your GSM gateway requires configuration or troubleshooting, Boardtac Solutions can help.

We provide professional diagnosis, configuration, troubleshooting, maintenance, installation, and support for IP phones, VoIP telephone systems, IP PBX platforms, Yeastar PBX systems, GSM gateways, SIP services, office extensions, and business communication networks.

Do not allow telephone system problems to interrupt communication with employees, customers, suppliers, or business partners.

Contact Boardtac Solutions for professional IP phone and VoIP telephone system support in Nairobi and across Kenya.

Boardtac Solutions — Reliable ICT, Business Communication and Security System Solutions.