Business Telephony: Part 3 — SIP Telephony Directly or an In-House PBX

A virtual PBX suits most small companies, but there are two options that are cheaper or give more control: a SIP account directly with a carrier and your own IP-PBX.

SIP telephony directly

In this option you get one or several SIP accounts from a telecom provider and configure phones or calling apps yourself.

How it works

1. Connecting to a provider. You choose a SIP provider (often the same companies that offer hosted PBX services), sign a contract and receive connection details: login, password and server address.
2. Choosing hardware and software:
   • softphones — apps for PC or smartphone, for example Zoiper, MicroSIP or PhonerLite: you enter the SIP account details and can make calls;
   • SIP phones — desk devices that connect to the network and are configured via a web interface;
   • VoIP gateways — devices for connecting ordinary analog phones to an IP network.
3. Configuration. Each phone or softphone is configured individually.

Advantages

• Low cost. Usually the cheapest way to use IP telephony: you pay for outgoing calls at the provider’s rates and possibly a small subscription fee for a number. There is no separate PBX fee.
• Freedom of equipment choice. Any device or app that supports SIP will work.
• Sufficient for one or two numbers. If complex call handling is not needed, this option is enough.

Disadvantages

• Minimum features. IVR, call queues, call recording and advanced call forwarding are usually absent or require additional setups and software.
• Configuration requires knowledge. Technical skills are needed to connect phones and softphones.
• No centralized management. Each device is configured separately.
• No unified statistics. Collecting and analyzing call data is difficult.

Your own IP-PBX

In this option you install and configure your own telephony server. It can be physical (a computer or a dedicated device in the office) or virtual (a rented VPS). Common IP-PBX software includes Asterisk, FreePBX, 3CX and MikoPBX; Asterisk, FreePBX and MikoPBX are distributed for free.

How it works

1. Install the PBX software on a server.
2. Connect SIP trunks — communication channels from one or several providers.
3. Configure call logic. The most complex stage: internal extensions, call routing, IVR, queues, call recording.
4. Connect employees via softphones or SIP phones.

Advantages

• Full control over all parameters of the phone system.
• Flexibility. You can implement almost any call handling logic and integrate with other company systems.
• Possible savings. After initial investments in equipment and setup, ongoing expenses may be lower than for a hosted PBX, especially with a large number of employees.
• Independence from a PBX provider. You can change your telecom provider without rebuilding the whole system.

Disadvantages

• Complexity of setup and maintenance. Deep technical knowledge or a specialist to maintain the system is required.
• Initial costs. A physical server requires equipment purchase; a cloud server requires monthly hosting fees.
• Responsibility for operation and security. You are responsible for outages and system protection. A PBX exposed to the Internet is constantly probed and attacked by password guessing so attackers can make expensive international calls at someone else’s expense; therefore you need strong passwords, a firewall and restrictions on call destinations.
• Time to deploy. Deployment and configuration take a noticeable amount of time.

Which fits whom

• SIP telephony directly — freelancers, sole proprietors and companies of one to three people who need the cheapest way to receive and make calls from a landline number without extra features.
• Your own IP-PBX:
  • companies with their own IT specialist or technically proficient owners;
  • businesses that need custom features or tight integration of telephony with other systems;
  • companies that value independence from providers;
  • large companies with many lines, where an in-house PBX may be more cost-effective in the long run.

Conclusion

The choice depends on company size, technical capabilities, budget and required features.

• Hosted PBX — simple, fast and functional, but with a monthly fee. Suits most small and medium companies.
• SIP telephony directly — cheap, but minimal features and more complex setup. Suits the smallest companies and individual work.
• Your own IP-PBX — maximum control and flexibility at the cost of significant technical knowledge and initial investment.