ISR4351-V/K9 – Secure Voice Gateway Router with SRST and CUBE
Product Overview
The Cisco ISR4351-V/K9 is a voice-enabled integrated services
router from the Cisco ISR 4000 Series, designed for medium to large
branch offices that require converged voice and data services,
secure WAN connectivity, and modular scalability. With the UC
(Unified Communications) license included, this router supports
SRST, CUBE, TDM voice, and video conferencing. The ISR4351-V/K9
delivers base performance of 200 Mbps, upgradeable to 400 Mbps,
making it ideal for IP telephony, SIP trunking, and secure
enterprise branch deployments.
Product Details
| Specification | Description |
|---|---|
| Product Code | ISR4351-V/K9 |
| Series | Cisco ISR 4000 Series |
| Form Factor | 2RU rack-mountable |
| Base Performance | 200 Mbps (upgradeable to 400 Mbps) |
| Built-in Interfaces | 4 x 1G RJ45, USB, Console |
| NIM Slots | 2 x Network Interface Module slots |
| SM Slots | 2 x Service Module slots |
| Voice Capability | Yes – with UC license included |
| Supported Voice Features | SRST, CUBE, SIP/H.323, TDM Voice Gateway |
| DRAM | 4 GB (upgradeable to 16 GB) |
| Flash Storage | 8 GB (upgradeable) |
| Power Supply | Optional dual redundant AC/DC |
| Software | Cisco IOS XE |
| SD-WAN Support | Yes (via SD-WAN image) |
| Security Features | ZBFW, IPsec VPN, CPPr (via SEC license) |
| High Availability | NSF, ISSU, redundant PSU/fans supported |
Product Features
Includes UC (Voice/Unified Communications) license for voice gateway functionality
Supports CUBE, SRST, SIP trunking, and PSTN TDM connectivity
Modular platform with 2 NIM + 2 SM slots for expansion (voice, WAN, LTE, switching)
Powered by Cisco IOS XE, enabling SD-WAN, automation, and advanced routing
Performance-on-demand licensing to scale throughput as business needs grow
Supports media-rich branch environments with video conferencing capabilities
Designed for resilient branch deployments with support for hardware redundancy
Similar Models Comparison
| Model | Voice License | Max Performance | NIM/SM Slots | SD-WAN Ready | Form Factor |
|---|---|---|---|---|---|
| ISR4351-V/K9 | Yes | 400 Mbps | 2 / 2 | Yes | 2RU |
| ISR4451-V/K9 | Yes | 2 Gbps | 3 / 2 | Yes | 2RU |
| ISR4331-V/K9 | Yes | 300 Mbps | 2 / 1 | Yes | 1RU |
| ISR4431-V/K9 | Yes | 1 Gbps | 2 / 1 | Yes | 1RU |
Latest Voice-Enabled ISR Models Comparison
| Model | Performance Range | UC Features | Ideal Use Case |
|---|---|---|---|
| ISR4351-V/K9 | 200 – 400 Mbps | SRST, CUBE, TDM Voice | Medium to large branch IP telephony |
| ISR4451-V/K9 | 1 – 2 Gbps | Full UC stack | Large branches needing voice + WAN |
| ISR4331-V/K9 | 100 – 300 Mbps | Basic UC, SRST | Small branch voice gateway |
