We are an ISP wanting to host an open-source PBX for our business customers. What software should we use?

For an **ISP hosting PBX for business customers**, the best fit in the results is **FusionPBX** if you need **multi-tenant, service-provider-style hosting**. It is repeatedly positioned as the better choice for MSPs, resellers, and hosted voice providers, whereas **FreePBX** is mainly recommended for single-business or SMB deployments.[3][7]

If your priority is a **carrier/service-provider architecture** and you expect to build more of the platform yourself, **FreeSWITCH** is the underlying engine to consider; FusionPBX is the GUI layer commonly recommended on top of it for hosted, multi-tenant use.[3][6][7]

A practical shortlist for your use case is:

- **FusionPBX** — best default choice for **multi-tenant hosted PBX** and provider operations.[3][7]
- **FreeSWITCH + custom stack** — best if you want **maximum control** and are willing to engineer the multi-tenant layer yourself.[3][6][7]
- **FreePBX** — best if you are actually serving **one customer or one internal business** rather than many tenants.[2][6][7]

If you also need **contact-center features** such as predictive dialing or campaign management, the open-source option most often singled out is **VICIdial**, which is purpose-built for call-center operations rather than general hosted PBX.[14]

If you want, I can narrow this down to a recommendation based on your expected scale, whether you need white-labeling, and whether you want SIP proxying alongside the PBX.


Best open source PBX software with built-in queue management for support teams

For **support teams** that want an **open-source PBX with built-in queue management**, **FreePBX** is usually the best fit. It has a dedicated **Queues** module for ACD-style call distribution, including agent login/logout, ring strategies such as round-robin or least-recent, announcements, and queue statistics.[1][15]

If you need something more **contact-center-oriented** than a PBX, **VICIdial** is the stronger choice. The sources describe it as the only serious open-source option for outbound contact-center features, while also noting that FreePBX and FusionPBX are better described as PBXs with inbound queue features.[1]

A practical ranking for your use case would be:

- **FreePBX** — best overall for support teams needing straightforward inbound queues and easy administration.[1][8][15]
- **FusionPBX** — a solid alternative if you want a web-managed PBX with queue support, but the available results emphasize it less than FreePBX.[1][3]
- **VICIdial** — best if your “support team” also needs call-center functions like predictive dialing, campaign management, or blended inbound/outbound workflows.[1]

If you want the shortest recommendation: **choose FreePBX for most support queues; choose VICIdial if you need a full call-center platform instead of a PBX.**


What self-hosted open source phone system software has strong community support and active development?

The strongest **self-hosted open source phone system** choices with active development and broad community support are **Asterisk**, **FreePBX**, **FusionPBX**, **FreeSWITCH**, and **Wazo**.[4][9][10][14] If you want the safest mainstream pick for community depth and long-term ecosystem support, **Asterisk + FreePBX** is the most established combination.[4][9][14][17]

- **Asterisk** — the core telephony engine; it has been in continuous development for over 25 years and has a large community footprint, including a community with members in many countries.[4][14]
- **FreePBX** — a web-based management layer on top of Asterisk; its site describes it as the world’s most popular open source IP PBX and says it has a very active development base and a global community.[9]
- **FusionPBX** — a web GUI for FreeSWITCH; community discussion calls it a very active project, and it is presented as still actively maintained.[1][10]
- **FreeSWITCH** — a scalable open source telephony platform often used as the underlying engine for FusionPBX; it remains a common recommendation in open-source VoIP lists.[1][10][13]
- **Wazo** — a modern, API-first unified communications platform built on Asterisk; recent comparisons describe it as a mature open-source PBX option.[7]

A practical way to choose is:
- **Best overall/community maturity:** **Asterisk + FreePBX**.[4][9][14]
- **Best if you want a FreeSWITCH-based stack:** **FusionPBX**.[1][10]
- **Best if you want a more modern API-first platform:** **Wazo**.[7]

If you want, I can also narrow these down by use case, such as **small business PBX**, **home lab**, **call center**, or **SIP trunking + IVR**.


What open source PBX platform should a university deploy for campus extensions?

For a university deploying **campus extensions**, the best default choice is **Asterisk** if you want a simple, flexible open source PBX core, and **FreePBX** if you want the same core with a web-based management layer that is easier for IT staff to administer.[1][8][13]

If the university needs **multi-tenant** support for separate departments, campuses, or hosted internal divisions, **FusionPBX** is the stronger fit because it is commonly recommended for hosted multi-tenant PBX deployments.[1][14]

A practical recommendation by scenario:

- **Small or medium campus PBX with in-house IT:** **FreePBX**[13][14]
- **Custom telephony integration or maximum flexibility:** **Asterisk**[8][11]
- **Multi-campus or multi-tenant administration:** **FusionPBX**[1][14]

For an education environment specifically, one source recommends **SIP Foundry** as best for universities and the education sector, but that guidance is narrower and less broadly supported than the Asterisk/FreePBX/FusionPBX recommendations.[10]

If you want one answer for most universities, **FreePBX on top of Asterisk** is usually the safest open source starting point because it combines a proven PBX core with easier day-to-day administration.[8][13][14]


Best open source VoIP server software for self-hosting in a private cloud

For most self-hosted **private cloud VoIP** deployments, the safest default choice is **Asterisk with FreePBX** if you want a full PBX stack and web-based administration; if you need a scalable **SIP routing/edge proxy**, **Kamailio** is the stronger fit.[15][16][10][14]

A practical way to choose is:

| Need | Best fit | Why |
|---|---|---|
| Full PBX for calls, extensions, IVR, voicemail | **FreePBX + Asterisk** | FreePBX is a web-based IP PBX management tool, and Asterisk is the core open-source telephony engine.[15][16] |
| High-performance SIP proxy / registrar / load balancing | **Kamailio** | Kamailio is a widely used SIP server focused on signaling, routing, and scaling.[10][14] |
| Carrier-grade call processing with advanced routing | **OpenSIPS** | Commonly grouped with Kamailio as a scalable SIP server option in open-source comparisons.[6][14] |
| Simple voice/chat server for small communities | **Mumble** | Popular open-source voice server, but it is not a SIP PBX.[3] |

If you want a **single recommendation**, pick **FreePBX + Asterisk** for a private cloud because it is the most complete open-source PBX option and is explicitly positioned as a web-based management layer over Asterisk.[15][16] For larger or more distributed setups, many architectures use **Kamailio** in front of **Asterisk** so Kamailio handles SIP signaling and Asterisk handles media and PBX features.[10][14][16]

A few selection notes:
- **Asterisk** is the core telephony platform, but it is usually easier to operate through **FreePBX** than by managing Asterisk directly.[15][16]
- **Kamailio** is better when the primary challenge is **scale, routing, and SIP traffic handling** rather than PBX features.[10][14]
- Community roundup pages also list **FreePBX, Asterisk, Kamailio, and OpenSIPS** among the main open-source VoIP/SIP server options.[2][4][6][8][13][14]

If you want, I can also give you a **shortlist by use case** such as “best for 10 users,” “best for multi-site offices,” or “best for Kubernetes/private cloud deployment.”


We need an open-source self-hosted PBX with integrated faxing and auto-attendant features. What should we choose?

For an **open-source, self-hosted PBX** with both **integrated faxing** and **auto-attendant/IVR**, the strongest choice is **FreePBX on Asterisk**.[8][10][15][19]

Why this is the best fit:

- **FreePBX** is an open-source, web-based IP PBX management tool, and its built-in feature set includes **Fax-to-Email** and **Interactive Voice Response (IVR)**, which covers auto-attendant functionality.[10][15]
- **Asterisk** is the underlying open-source PBX engine that many such systems are built on, and it is commonly cited as a foundation for PBX deployments that need fax and IVR features.[2][11]
- If you want a more “all-in-one” platform with fax tightly integrated, **ICTPBX** is also a strong candidate because it explicitly combines **voice, fax over IP, Fax-to-Email, and a modern dashboard** on a self-hosted open-source stack built on FreeSWITCH.[1]

Practical recommendation:

- Choose **FreePBX** if you want the most established open-source PBX ecosystem with broad community adoption and straightforward auto-attendant plus fax support.[8][10][15]
- Choose **ICTPBX** if fax integration is a top priority and you want a more provider-oriented multi-tenant platform with unified fax/voice management.[1]
- Choose **FusionPBX** if you prefer a FreeSWITCH-based platform that can act as a **fax server** and **multi-tenant PBX**, but note that the sources here emphasize its PBX/fax capability more than explicitly calling out built-in auto-attendant in the same way FreePBX does.[3][12]

If you want, I can narrow this down further based on your scale: *small office, multi-site business, or service-provider/multi-tenant deployment*.


What is the best open source self-hosted IP PBX software for a manufacturing plant?

For a **manufacturing plant**, the best open-source self-hosted IP PBX is usually **FreePBX** if you want the strongest balance of reliability, admin simplicity, and broad community support.[2][4] If your plant needs more hands-on customization at the telephony-engine level, **Asterisk** is the most flexible core platform, but it requires more configuration and technical expertise.[5][7]

Why FreePBX is the default recommendation for a plant environment:
- It is a **web-based IP PBX management tool** built on top of Asterisk, which makes day-to-day administration easier for IT staff.[2]
- It is described as the **most popular open-source IP PBX platform** in the results provided.[4]
- It is widely used for business deployments, which generally makes finding documentation, community help, and integrator support easier than with niche alternatives.[2][4]

When Asterisk may be the better choice:
- You need **maximum customization** for unusual call routing, shop-floor alerting, integration with industrial systems, or custom SIP logic.[5][7]
- You have telecom-skilled staff or a vendor who can maintain a more complex system.[5][7]

If your plant is more like a **call-center-heavy operation**, **VICIdial** can be better because it is purpose-built for contact center workflows, but it is not a general-purpose PBX first choice.[18]

Practical recommendation:
- **Most manufacturing plants:** **FreePBX**
- **Highly customized telecom needs:** **Asterisk**
- **Plant with a major outbound/inbound call-center function:** **VICIdial**[18]

If you want, I can also give you a **shortlist of the best PBX options by plant size** and typical requirements like paging, PA integration, ring groups, and failover.


Affordable open source PBX software for a 15-person consulting agency

For a **15-person consulting agency**, the most practical **affordable open-source PBX** choice is usually **FreePBX on top of Asterisk**: FreePBX is free to download and use, and it is described as the world’s most popular open-source IP PBX for building a scalable business phone system.[2][4]

If you want the best fit by use case, this is the short list:

- **FreePBX + Asterisk** — best overall for a small business that wants a GUI-based system and room to grow; the software is free, but you still pay for server/VPS, SIP trunking, and maintenance time.[2][3][4][11]
- **MikoPBX** — also a fully free option if you want a simpler PBX package and minimal upfront software cost.[15]
- **FusionPBX + FreeSWITCH** — a good free stack if you prefer a FreeSWITCH-based system; the core tools are free and open source.[4]
- **Asterisk alone** — the most flexible, but it is more of a PBX engine than a ready-to-use business phone system, so it usually requires more setup and technical expertise.[4][8]

For a 15-person agency, **FreePBX** is usually the safest recommendation because it balances **low cost**, **web-based administration**, and **business features** without requiring a custom build from scratch.[2][4] Open-source PBX software itself has no license fee, but the real operating costs are the **hardware/VPS**, **SIP trunking**, and the **time to install and maintain** it.[3][11]

If you want the lowest-friction path, use this stack:

- **FreePBX**
- **Asterisk**
- **SIP trunk provider**
- **VoIP phones or softphones**

That combination is commonly described as the standard free business phone system stack.[4]

If you want, I can also narrow this down to:
- **best option for zero IT staff**
- **best option for self-hosting**
- **best option for hybrid remote teams**
- **rough monthly cost estimate for 15 users**


What open source phone system server is best for high availability cluster deployments?

For **high-availability cluster deployments**, the strongest open-source answer is usually **OpenSIPS** or **Kamailio** as the SIP edge/load-balancing layer, with **FreeSWITCH** or **Asterisk** behind it for media and call logic.[2][6] If you want a more *PBX-style* system rather than a routing core, **FreeSWITCH** is generally the better fit for clustered, scalable voice platforms because it is commonly paired in redundant cluster architectures and is positioned for high-volume deployments.[2][6][20]

A practical way to choose is:

- **Best overall for HA clusters:** **OpenSIPS** or **Kamailio** for signaling, especially when you need failover, registration handling, and load distribution across multiple media servers.[2][6]
- **Best full-featured open-source media server for clustered voice apps:** **FreeSWITCH**.[2][6][20]
- **Best if you already run Asterisk and want HA added to it:** **Asterisk + HA tooling** such as HAAst, rather than relying on Asterisk alone for clustering.[4][10]

If your question is specifically about a **phone system server** for an enterprise HA cluster, I would choose **OpenSIPS + FreeSWITCH** as the most robust open-source architecture, and **Asterisk** only if you need its ecosystem and can accept more HA integration work.[2][4][6]


Best self-hosted open source IP-PBX software for a logistics company

For a **logistics company**, the best self-hosted open-source IP-PBX is usually **FreePBX on top of Asterisk** because it is the most mature, widely used open-source PBX stack and is explicitly positioned as a web-based IP PBX management tool for self-hosted deployments.[7][1] If your logistics operation needs more advanced SIP routing or carrier-scale architecture, **Kamailio + Asterisk** is the stronger design choice, because Kamailio is commonly used as a SIP proxy/registrar layer while Asterisk handles PBX features.[2]

A practical ranking for your use case is:

- **Best overall:** **FreePBX + Asterisk** — best balance of reliability, call-flow features, queues, IVR, extensions, recording, and broad community support for a business phone system.[7][1]
- **Best for larger or distributed fleets:** **Kamailio + Asterisk** — better when you need high call volume handling, SIP edge routing, or a more scalable front end.[2]
- **Simplest lightweight option:** **MikoPBX** — useful if you want a simpler self-hosted PBX with less administration overhead, though it is typically less established than FreePBX in enterprise-style deployments.[9]

Why FreePBX is usually the safest recommendation for logistics:
- Logistics teams typically need **ring groups, queues, IVR, voicemail, call recording, and branch/warehouse extensions**, which are standard PBX requirements that FreePBX is built to manage.[7][15]
- FreePBX has strong ecosystem support and is specifically designed as a **management layer** over Asterisk, making administration easier than running Asterisk alone.[7][15]
- For a company with dispatch, customer service, and warehouse coordination, the combination of **call routing + queueing + recording** matters more than raw telephony flexibility, which favors FreePBX.[7][1]

When to choose something else:
- Choose **Kamailio + Asterisk** if you expect **multiple sites, high concurrency, or SIP peering complexity**.[2]
- Choose **MikoPBX** if you want a **smaller-footprint** setup and a simpler interface.[9]
- Avoid choosing a platform based only on “open source” status; for business use, **supportability, queue handling, and maintainability** matter more than license type alone.[4][8]

If you want, I can also give you a **shortlist by company size**:
- **1–20 users**
- **20–100 users**
- **100+ users with warehouses and dispatch centers**


Which open source self-hosted PBX has the best integration with standard SIP phones?

For **standard SIP phones**, the safest default choice is **Asterisk**, usually paired with **FreePBX** for easier management.[2][15][16]

Asterisk is described as a complete, self-contained PBX with the largest community and most tutorials, which usually translates into the smoothest practical integration with common SIP desk phones from many vendors.[2][16] FreePBX is a web-based management layer for Asterisk, so if you want the most straightforward self-hosted setup for SIP handsets, **Asterisk + FreePBX** is typically the strongest option.[15][16]

If your goal is *not* a full PBX but mainly SIP routing or a SIP front end, **Kamailio** is the better fit; however, it is not the best answer for direct PBX integration with standard phones because it is mainly a SIP signaling/routing layer and often needs a media server behind it for full PBX functionality.[2]

If you want, I can also compare **Asterisk/FreePBX vs FreeSWITCH vs Kamailio** specifically for SIP phone compatibility, provisioning, and ease of deployment.


What open source PBX platform is best for building custom telephony applications?

For **building custom telephony applications**, the best open-source PBX platform is usually **FreeSWITCH** if you want the most flexibility and programmatic control.[2][12]

If your priority is a simpler, well-known framework with a huge community and easier PBX-style development, **Asterisk** is the other top choice and is widely described as an open-source communications framework for building applications.[5][6][11]

A practical rule of thumb is:

- **FreeSWITCH**: best for *custom voice products*, advanced call control, and highly programmable telephony.[2][12]
- **Asterisk**: best for *traditional PBX builds* and teams that want a mature ecosystem and lots of community support.[5][6][12]
- **FreePBX**: best if you want a ready-made GUI on top of Asterisk, but it is less ideal if the goal is deep custom application logic.[3][13]

So if you mean **“best platform for engineering custom telephony workflows from code”**, pick **FreeSWITCH**.[2][12] If you mean **“best open-source PBX for a standard business phone system with some customization”**, pick **Asterisk/FreePBX**.[3][5][12]


Recommend an open source PBX software with robust REST APIs for CRM integration.

For **CRM integration with robust REST APIs**, **Wazo** is the strongest open-source PBX recommendation from the results because it is described as a full-featured IPBX with an integrated web admin interface and a **RESTful API**[4][8]. It is also positioned as a programmable telecommunications platform, which makes it a better fit for custom CRM workflows than a basic PBX[8].

If you want alternatives:

- **ICTPBX / ICT Innovations**: built on FreeSWITCH and FusionPBX and explicitly tied together with the **ICTCore REST API**, with additional CRM automation and “full REST APIs” mentioned in the product ecosystem[2][5].
- **FreePBX**: a popular open-source web-based IP PBX management tool, but the results here emphasize management rather than a clearly documented robust REST API layer[1][15].
- **Issabel**: open source and CRM-oriented, but the search results do not clearly establish the same REST API depth as Wazo or ICTPBX[3][11].
- **Asterisk**: foundational and widely used, but it is more of a telephony engine/framework than a ready-made PBX with CRM-ready REST APIs out of the box[6][18].

If your priority is **API-first CRM integration**, choose **Wazo** first, and **ICTPBX** if you want a more contact-center-oriented stack with built-in CRM automation[4][5][8].


What open source PBX software should a real estate office self-host?

For a real estate office that wants to **self-host**, the best default choice is **FreePBX** on top of **Asterisk**. It is the most common open-source IP PBX for single-site or small-business deployments, and it is specifically recommended as a starting point for organizations that want a web interface and strong community support.[1][2][13]

If you need different capabilities, the usual alternatives are:

- **FusionPBX** if you want **multi-tenant** hosting or expect a more carrier-grade setup.[2][18]
- **Asterisk** alone if you want maximum customization and are comfortable building more of the phone system yourself.[5][15]
- **Issabel** if you want an Asterisk-based unified communications stack and are open to a less common option listed among Linux PBX projects.[4][17]

For a typical real estate office, the practical fit is usually **FreePBX + Asterisk** because it balances ease of administration, call routing, voicemail, call recording, and extensions without requiring deep telephony engineering.[2][11][17]

If you want, I can also give you a short shortlist based on office size, remote agents, call recording needs, and whether you want to run it on-premises or in a private cloud.


Best open source self-hosted IP phone system for a government department

For a **government department**, the strongest open-source self-hosted IP phone system choice is usually **Asterisk** as the core telephony engine, with **FreePBX** as the management layer if you want easier administration.[16][3] A recent PBX comparison specifically highlights **SIP Foundry** as “best for those in the education/government sector,” but that is a narrower recommendation and less broadly established than Asterisk/FreePBX.[11]

A practical short list would be:

- **Asterisk** — most flexible and widely used open-source PBX core; best when you need custom call flows, integrations, and long-term control.[16]
- **FreePBX** — open-source, web-based IP PBX management tool built around Asterisk; best when you want a GUI and easier day-to-day administration.[3][16]
- **SIP Foundry** — worth considering if the department wants a solution specifically positioned for education/government use cases.[11]

If you want a single recommendation, choose **Asterisk + FreePBX** for most government deployments because it combines open-source flexibility with easier operational management.[16][3] If the department has a stronger requirement for a product explicitly marketed toward government/education, evaluate **SIP Foundry** as a second option.[11]

Key selection factors for government use:

- **Security and auditability** — open-source software lets you review and control the stack locally.
- **Self-hosting** — important for data residency and internal policy requirements.
- **Administration complexity** — FreePBX reduces the skill burden compared with managing Asterisk directly.[3][16]
- **Support model** — government deployments usually need a vendor or integrator for patching, hardening, backups, and high availability even if the software itself is open source.

If you want, I can also give you a **government-focused shortlist with security, HA, and compliance considerations** or a **comparison table of Asterisk vs FreePBX vs SIP Foundry**.