United States$5,000,000+
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Nathan Brooks
5
Cisco SRST881 ensures reliable FXS/FXO connectivity with minimal downtime. Perfect for small office voice and secure routing needs.
C881SRST-K9
Cisco SRST881 ENet FXS - FXO Sec Router
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Name:
C881SRST-K9
- Description:
- Cisco SRST881 ENet FXS - FXO Sec Router
- Rating:
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- Brand:
- Cisco
- GTIN:
- 882658171482
- Condition:
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C881SRST-K9 Overview
C881SRST-K9 is a fixed enterprise router engineered for branch offices that demand secure, integrated services and reliable voice capabilities even in adverse network conditions. Designed with a robust architecture, it supports multiple routing protocols and integrated VPN features, ensuring secure data and voice transmission across WAN and LAN interfaces with high throughput and redundancy for mission-critical use cases.
C881SRST-K9 combines versatile power options with a streamlined front-panel design that facilitates rapid deployment in diverse environments. With integrated services such as advanced firewall protection, SRST for voice survivability, and modular capabilities for future expansion, it meets the performance and connectivity requirements of enterprise and branch office infrastructures.
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C881SRST-K9 Specifications
- Power Source
- AC Power Supply
- Memory
- 256 MB
- Flash Memory
- 128 MB
- Ethernet Technology
- 10/100
- Form Factor
- Desktop
- Weight
- N/A
- Height
- N/A
- Depth
- N/A
- Width
- N/A
- Product Type
- Enterprise Router
- Architecture
- Fixed
- Wi-Fi Standard
- N/A
- Connectivity Type
- Wired
- Wireless Support
- No
- Firewall Features
- Yes
- Management
- Managed
- Safety
- N/A
- EMC
- N/A
- Telecom
- N/A
- QoS Features
- Supported
- Stacking Capability
- No
- 5G Support
- No
- Interface Ports
- RJ-45
- Device Type
- Router
- WAN Configuration
- WAN
- Network Protocols
- IPv4, IPv6
- High Availability Support
- Supported
- Throughput Capacity
- 0.025 Gbps
- LAN Ports
- 4 LAN Ports
- Compliance Standards
- FCC, CE, RoHS
- WAN Ports
- 1 WAN
- Built-in Security Features
- Firewall, Intrusion Prevention, Malware Protection
- Broadband
- DSL
- VPN Support
- IPSec / DMVPN / FlexVPN
- Remote Management
- SSH / Telnet / SNMP
- Modular Slots Available
- N/A
- Expansion Slots
- N/A
- Routing Protocols
- OSPF / EIGRP / RIP / BGP / Static Routing
- Power
- 20W
- Speed/Capacity
- 25 Mbps
- Features
- VPN, NAT, Firewall, QoS, SRST, Voice, Integrated Security
- Use Case
- Enterprise, Branch Office
- Integrated Services
- Voice, Secure WAN, Unified Communications
- Product Name
- Cisco 881SRST-K9 Integrated Services Router
C881SRST-K9 Use Case
Branch Office Telephony Continuity with PSTN Fallback
In a multi-site enterprise running Cisco Unified Communications Manager, a WAN disruption can interrupt IP telephony. Deploying the C881SRST-K9 SRST881 ENet FXS-FXO router in each branch enables Survivable Remote Site Telephony (SRST). When the primary WAN link fails, the FXO port automatically routes inbound/outbound voice calls over the local PSTN circuit, maintaining uninterrupted voice service. Benefit: zero downtime for critical business calls, enhanced customer experience, and compliance with continuity SLAs.
Secure Site-to-Site VPN for Remote Branch Connectivity
A financial services firm requires encrypted connectivity between its data center and distributed offices. The Cisco SRST881 C881SRST-K9 integrates a high-performance IPsec VPN gateway, firewall, and ACLs to establish secure tunnels over the public Internet. Using built-in AES-256 encryption and centralized Cisco Security Manager policies, remote sites exchange sensitive data and VoIP traffic without exposure. Benefit: end-to-end data confidentiality, simplified VPN management, and reduced hardware footprint at each branch.
Legacy Analog Device Integration in Healthcare Clinics
A chain of outpatient clinics relies on analog fax machines and patient emergency phones alongside IP phones. The C881SRST-K9’s two FXS ports connect analog endpoints directly, while its router and security features protect clinical data on the LAN. Clinicians can fax prescriptions and use bedside phones, and in the event of a network outage, SRST mode preserves analog call paths. Benefit: seamless unification of analog and VoIP devices, cost-effective deployment, and uninterrupted patient communication.
Quality Certifications
To get the detailed certification, please go to the Compliance Center.
Product Comparison Table
 C881SRST-K9 |  CISCO857W-G-A-K9 |  CISCO878-SEC-K9 |  CISCO851-K9 |  CISCO877-SEC-K9 | |
|---|---|---|---|---|---|
| 5G Support | No | No | No | No | No |
| Architecture | Fixed | Fixed | Fixed | Fixed | Fixed |
| Broadband | DSL | N/A | DSL | N/A | DSL |
| Built-in Security Features | Firewall, Intrusion Prevention, Malware Protection | Firewall / Intrusion Prevention / Malware Protection | Firewall / Intrusion Prevention / Malware Protection | Firewall / Intrusion Prevention / Malware Protection | Firewall / Intrusion Prevention |
| Compliance Standards | FCC, CE, RoHS | FCC / CE / UL | FCC / CE | FCC, CE | FCC / CE |
| Connectivity Type | Wired | Wired / Wireless / Ethernet | Wired | Wired | Wired |
| Depth | N/A | N/A | N/A | 8.0 inches | N/A |
| Device Type | Router | Router | Router | Router | Router |
| EMC | N/A | N/A | N/A | N/A | N/A |
| Ethernet Technology | 10/100 | 10/100 | 10/100 | 10/100 | 10/100 |
| Expansion Slots | N/A | N/A | N/A | N/A | N/A |
| Features | VPN, NAT, Firewall, QoS, SRST, Voice, Integrated Security | VPN / VoIP / IPv6 Compatible / Firewall | VPN / IPv6 Compatible / Firewall | VPN / IPv6 Compatible / Firewall | VPN / IPv6 Compatible / Firewall |
| Firewall Features | Yes | Yes | Yes | Yes | Yes |
| Flash Memory | 128 MB | 128 MB | 256 MB | 128 MB | 256 MB |
| Form Factor | Desktop | Desktop | Desktop | Desktop | Desktop |
| Height | N/A | N/A | N/A | 1.0 inches | N/A |
| High Availability Support | Supported | Supported | Not Supported | Not Supported | Not Supported |
| Integrated Services | Voice, Secure WAN, Unified Communications | Voice / Video / WAN Optimization | Voice | Voice / Video | Voice |
| Interface Ports | RJ-45 | RJ-45 / SFP | RJ-45 | RJ-45 | RJ-45 |
| LAN Ports | 4 LAN Ports | 4 LAN Ports | 4 LAN Ports | 4 LAN Ports | 4 LAN Ports |
| Management | Managed | Managed | Managed | Managed | Managed |
| Memory | 256 MB | 256 MB | 256 MB | 256 MB | 512 MB |
| Modular Slots Available | N/A | N/A | N/A | N/A | N/A |
| Network Protocols | IPv4, IPv6 | IPv4, IPv6, TCP, UDP, ICMP | IPv4 / IPv6 / NAT | IP, IPv6, QoS | IPv4 / IPv6 |
| Power | 20W | 65W | 18W | 22.8 Watt | 25W |
| Power Source | AC Power Supply | AC Power Supply / DC Power Supply / Redundant | AC Power Supply | AC Power Supply / Redundant | AC Power Supply |
| Product Name | Cisco 881SRST-K9 Integrated Services Router | CISCO857W-G-A-K9 Integrated Services Router | CISCO878-SEC-K9 Secure Router | Cisco 851 Wireless Services Router | CISCO877-SEC-K9 |
| Product Type | Enterprise Router | Enterprise Router | Integrated Services Router | Enterprise Router | Enterprise Router |
| QoS Features | Supported | Supported | Supported | Supported | Supported |
| Remote Management | SSH / Telnet / SNMP | CLI, SNMP, Telnet, SSH | HTTP / HTTPS / SNMP / Telnet / SSH | Telnet, SSH, SNMP | Telnet / SSH |
| Routing Protocols | OSPF / EIGRP / RIP / BGP / Static Routing | OSPF / BGP / EIGRP / RIP / Static Routing | OSPF / RIP / Static Routing | OSPF / BGP / EIGRP / RIP / Static Routing | OSPF / EIGRP / RIP / Static Routing |
| Safety | N/A | N/A | N/A | N/A | N/A |
| Speed/Capacity | 25 Mbps | N/A | Fast Ethernet | Gigabit | N/A |
| Stacking Capability | No | No | No | No | No |
| Telecom | N/A | N/A | N/A | N/A | N/A |
| Throughput Capacity | 0.025 Gbps | 100 Mbps | 50 Mbps | 0.025 Gbps | 0.01 Gbps |
| Use Case | Enterprise, Branch Office | Enterprise | Small Business / Branch Office | Enterprise | Small Business |
| VPN Support | IPSec / DMVPN / FlexVPN | IPSec / SSL VPN / DMVPN | IPSec / DMVPN / FlexVPN | IPSec / SSL VPN / N/A | IPSec / SSL VPN |
| WAN Configuration | WAN | Dual WAN | WAN | WAN | WAN |
| WAN Ports | 1 WAN | 2 WAN | 1 WAN | 1 WAN | 1 WAN |
| Weight | N/A | N/A | N/A | 4.5 lbs | N/A |
| Wi-Fi Standard | N/A | WiFi 4 / Dual band | N/A | WiFi 4 | N/A |
| Width | N/A | N/A | N/A | 9.0 inches | N/A |
| Wireless Support | No | Yes | No | Yes | No |
Reviews & Ratings
E
Emma Foster
4
Dependable SRST router. Handles voice failover seamlessly and keeps business communications running smoothly.
R
Ryan Matthews
5
Easy to configure with predictable uptime. Cisco quality ensures stable voice and network performance.
C
Chloe Bennett
3
Solid performance for FXS/FXO lines. Reliable backup solution for small office telephony systems.
L
Liam Thompson
4
Efficient and dependable router. Ensures uninterrupted communication with easy management.
Questions & Answers
What is the Cisco SRST881 ENet FXS-FXO Sec Router (SKU: C881SRST-K9)?
The Cisco SRST881 ENet FXS-FXO Sec Router (C881SRST-K9) is a secure branch-office router that integrates Survivable Remote Site Telephony (SRST), multiport Ethernet, analog voice ports, and advanced security features in a compact desktop form factor.
What are the key features of the Cisco C881SRST-K9 router?
Key features include 8 10/100 Ethernet ports, 2 FXS and 2 FXO analog voice ports, SRST for Cisco Unified Communications survivability, stateful firewall, intrusion prevention, and IPsec VPN support.
How many Ethernet, FXS, and FXO ports does the SRST881 support?
The SRST881 provides 8 10/100 Ethernet ports for LAN/WAN connectivity, 2 FXS ports for IP phone fallback, and 2 FXO ports for PSTN connectivity in survivable mode.
What is Survivable Remote Site Telephony (SRST) and how does the C881SRST-K9 implement it?
SRST is Cisco’s failover telephony feature that keeps IP phones operational during WAN outages; the C881SRST-K9 hosts a built-in SRST application to maintain call processing locally.