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Description
Grandstream SIP ATA FXO/ FXS Gateway | HT-813Bridge Your Analog and VoIP Worlds with the Grandstream HT813 The Grandstream HT813 is a powerful and compact hybrid analog telephone adapter (ATA) designed to seamlessly integrate your traditional analog telephone devices with a modern VoIP network. This versatile gateway features one analog telephone FXS port and one PSTN line FXO port, enabling you to leverage the benefits of VoIP while maintaining a connection to your existing landline. The HT813
Bridge Your Analog and VoIP Worlds with the Grandstream HT813
The Grandstream HT813 is a powerful and compact hybrid analog telephone adapter (ATA) designed to seamlessly integrate your traditional analog telephone devices with a modern VoIP network. This versatile gateway features one analog telephone FXS port and one PSTN line FXO port, enabling you to leverage the benefits of VoIP while maintaining a connection to your existing landline. The HT813 is the perfect solution for small businesses and home users looking to upgrade to a flexible and cost-effective communication system.
Key Features and Benefits
- Hybrid Connectivity: Equipped with both an FXS port to connect an analog phone or fax machine and an FXO port for a PSTN line, the HT813 offers a unique and flexible communication solution.
- Lifeline Support: In the event of a power outage, the HT813 provides lifeline support by automatically relaying the FXS port to the FXO port, ensuring you can still make and receive calls on your traditional landline.
- Advanced VoIP Functionality: Supports 2 SIP profiles, 3-way voice conferencing per port, and a failover SIP server that automatically switches to a secondary server if the main one loses connection.
- Reliable Fax over IP: Features support for the T.38 Fax protocol, ensuring reliable and efficient faxing over your IP network.
- Robust Security: Your calls and accounts are protected with strong AES encryption and a unique security certificate per unit.
- Easy Provisioning and Management: Offers automated and secure provisioning options using TR-069, simplifying deployment and management.
Technical Specifications
| Interfaces | One (1) RJ11 FXS port, One (1) RJ11 FXO PSTN line port with lifeline support |
| Network Interface | Two (2) 10/100Mbps ports (RJ45) with integrated NAT router |
| LED Indicators | POWER, LAN, WAN, FXS, FXO |
| Factory Reset Button | Yes |
| Telephony Features | Caller ID display or block, call waiting, flash, blind or attended transfer, forward, hold, do not disturb, 3-way conference |
| Voice Codecs | G.711 with Annex I (PLC) and Annex II (VAD/CNG), G.722, G.723.1, G.729A/B, G.726, iLBC, OPUS, dynamic jitter buffer, advanced line echo cancellation |
| Fax over IP | T.38 compliant Group 3 Fax Relay up to 14.4kpbs and auto-switch to G.711 for Fax Pass-through |
| Short/Long Haul Ring Load | 3 REN: Up to 1km on 24 AWG |
| Caller ID | Bellcore Type 1 & 2, ETSI, BT, NTT, and DTMF-based CID |
| Disconnect Methods | Busy Tone, Polarity Reversal/Wink, Loop Current |
| Network Protocols | TCP/IP/UDP, RTP/RTCP, HTTP/HTTPS, ARP/RARP, ICMP, DNS, DHCP, NTP, TFTP, TELNET, STUN, SIP (RFC3261), SIP over TCP/TLS, SRTP, TR-069 |
| QoS | Layer 2 (802.1Q VLAN, 802.1p) and Layer 3 (ToS, DiffServ, MPLS) |
| DTMF Method | In-audio, RFC2833 and/or SIP INFO |
| Provisioning and Control | HTTP, HTTPS, TELNET, TFTP, TR-069, secure and automated provisioning using AES encryption |
| Security | SRTP, TLS/SIPS/HTTPS |
| Physical | Universal Power Supply: Input: 100-240VAC, 50-60Hz, Output: 12V/0.5A |
| Environmental | Operating: 32º – 104ºF or 0º – 40ºC, Storage: 14º – 140ºF or -10º – 60ºC, Humidity: 10 – 90% Non-condensing |
| Dimensions and Weight | 25mm x 115mm x 75mm (H x W x D) |
| Compliance | FCC, CE, RCM |
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4.8 ★★★★★
Based on 28 reviews
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Product Reviews
★★★★★ 5
Compelling, informative, and accurate
Format: Kindle
I really could not be happier with the pace and level of detail this book provides. I am a very surface-level Linux user and I wanted to dive in head first. I often find that when I learn about something that I consider really hard or intimidating in tech, I get better at day-to-day use of the tools and my confidence grows. This book is a real confidence-booster if you crave the knowledge of how things work under the hood.
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Reviewed in the United States on October 8, 2024
★★★★★ 5
Great book to read
Format: Paperback, Format: Paperback
Great book to keep you updated about upstream Linux
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Reviewed in the United States on March 18, 2024
★★★★★ 5
A Hands-On and Deep Guide to Linux Kernel Programming
Format: Paperback
Linux Kernel Programming, Second Edition is a very practical and well-structured book for anyone who wants to understand how the Linux kernel works. It focuses on both theory and real hands-on learning. The book uses a clear style and explains complex topics in a simple way. It is designed to help readers build real skills, not just read concepts. It is especially useful for developers who want to work closer to the operating system.
One of the most interesting parts of the book is the strong introduction to kernel programming. It explains how to set up a development environment, build the Linux kernel from source, and write the first kernel module. This section gives readers a solid starting point and builds confidence early in the learning process. It also explains why loadable kernel modules are widely used in real-world projects.
Another highlight is the deep coverage of kernel internals. The book explains core concepts such as kernel architecture, processes, threads, and the difference between user mode and kernel mode. These ideas are often hard to understand, but the book presents them in a clear and structured way. This helps readers see how the operating system really works under the surface.
The memory management section is especially strong and detailed. The book spends several chapters explaining how memory is allocated and managed inside the kernel. It also explains advanced topics such as page allocation, memory reclaim, and the out-of-memory system. These chapters are very useful for understanding performance and stability in real systems.
Another very interesting section is the coverage of CPU scheduling. The book explains how the Linux kernel decides which task runs at a given time. It introduces scheduling policies, priorities, and modern features like control groups. The explanations are practical and supported by examples, which makes the topic easier to follow.
The chapters on kernel synchronization are also a major highlight. They explain concepts such as locks, atomic operations, and deadlock prevention. These topics are critical for writing safe and reliable kernel code. The book also shows real examples and common mistakes, which helps readers avoid problems in their own work.
Another strength of the book is its hands-on approach. It includes many kernel modules, scripts, and examples that readers can try themselves. This makes learning more engaging and helps turn theory into real skills. The focus on practical work makes the book stand out from more theoretical resources.
Overall, this book is a great choice for developers, system programmers, and engineers who want to understand the Linux kernel in depth. It starts with the basics and moves into advanced topics in a smooth way. The combination of clear explanations and practical examples makes it a strong and valuable learning resource.
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Reviewed in the United States on April 16, 2026
★★★★★ 4
Poor quality binding
Format: Paperback, Format: Paperback
Binding glue fell apart in less than a week and the pages fell out. Content is great though and I have a shiny new kernel based on Kali. 4 stars despite the binding because the content is top tier if you love all things Linux 🤌
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Reviewed in the United States on July 4, 2025
★★★★★ 5
An Essential Guide for Mastering Linux Kernel Development
Format: Paperback, Format: Paperback
Linux Kernel Programming - Second Edition: A Comprehensive and Practical Guide to Kernel Internals, Writing Modules, and Kernel Synchronization is an outstanding resource for anyone eager to understand the inner workings of the Linux kernel. Whether you're a beginner looking to get started or an experienced developer aiming to deepen your knowledge, this book delivers a well-structured and hands-on approach to kernel programming.
The book starts with the fundamentals—setting up a kernel development environment, understanding kernel release nomenclature, and compiling the 6.x Linux kernel from source. As you progress, it dives into advanced topics such as kernel configuration, writing and debugging loadable kernel modules (LKMs), kernel synchronization mechanisms, memory management, CPU scheduling, and much more. Each chapter builds on practical examples, ensuring that readers not only understand the theory but also learn how to apply it in real-world scenarios.
One of the book's biggest strengths is its focus on practical application. From exploring the kernel build process and bootloader configurations to working with Git for kernel development and troubleshooting system crashes using debugging tools, the book provides step-by-step guidance. The coverage of kernel synchronization techniques—including spinlocks, mutexes, and RCU—makes it an invaluable reference for those dealing with concurrent programming in the kernel space.
Whether you're an aspiring kernel developer, a DevOps engineer, or a systems programmer, this book is a must-have. The clear explanations, well-structured content, and hands-on exercises make it a perfect companion for anyone wanting to go from a beginner to an expert in Linux kernel programming.
Highly recommended for anyone serious about understanding and working with the Linux kernel!
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Reviewed in the United States on January 29, 2025