This is a pdf about cisco 2901 router.

1. Cisco 2901 Specs
The Cisco 2901 router, supporting voice module, is designed for small offices.
Cisco 2901 Specs
Release Date: 13-OCT-2009
AC Input Voltage: 100 to 240 VAC auto ranging
Compact Flash (External) - Default: slot 0: 256 MB; slot 1: none
Maximum End-Point PoE Power Capacity with PoE Boost (Watts): n/a
Airflow: Front to side
SFP-Based Ports: 0
Temperature: 9,843 feet (3,000m ) Maximum Altitude : 32 to 77 F (0 to 25 C)
ISM Slots: 1
Modular LAN Switchports (with optional PoE): 16
Altitude: 10,000 ft (3,000m)
DC Input Voltage: n/a
Compact Flash (External) - Maximum: slot 0: 4 GB; slot 1: 4 GB
Temperature: 13,123 feet (4,000m) Maximum Altitude : n/a
Cisco Unified SRST Sessions: 35
Memory DDR2 ECC DRAM - Maximum: 2 GB
Onboard DSP (PVDM) Slots: 2
Wall-Mount (refer to installation guide for approved orientation): Yes
Double-Wide Service Module Slots: 0
Power Supply: AC and PoE
Serial console port: 1
Acoustic: Sound Pressure (Typical/Maximum): 41/53 dBA
Maximum Power with PoE Power Supply (Platform Only) (Watts): 175
AC Input Current Range AC Power Supply (Maximum): 1.5 to 0.6 A
Maximum Power with DC-PoE Power Supply (Platform Only) (Watts): n/a
Dimensions (H x W x D):
1.75 x 17.25 x 17.3 in. (44.5 x 438.2 x 439.4
mm)
Rack Mounting Kit: Included
Weight with AC PoE Power Supply (No Modules): 14.3lb (6.5 kg)
RPS Support (External): No
EHWIC Slots: 4
Short-Term (per NEBS) Humidity : n/a

2. Cisco Unified CCME Sessions: 35
Typical Weight Fully Configured : 16 lb (7.3 kg)
External USB 2.0 Flash Memory Slots (Type A): 2
AC Input Surge Current: < 50A
Integrated WAN Ports: 2 GE
Non-Operating Temperature: -40 to 158 F (-40 to 70 C)
Relative Humidity: 10 to 85%
Acoustic: Sound Power (Typical/Maximum): 49/61 dBA
Temperature: Short-Term (per NEBS) 5906 feet (1,800m) Maximum Altitude: n/a
Temperature: 5,906 feet (1,800m) Maximum Altitude : 32 to 104 F (0 to 40 C)
Non-Operating Relative Humidity: 5 to 95%
Maximum End-Point PoE Power Available from DC PoE Power Supply (Watts):n/a
Weight with AC Power Supply (No Modules): 13.4 lb (6.1 kg)
Serial auxiliary port: 1
Embedded Hardware-Based Cryptography and Acceleration: Yes
USB Console Port (Type B) (up to 115.2 kbps): 1
RJ-45-based ports: 2
Optional Airflow Kit: n/a
Memory DDR2 ECC DRAM - Default: 512 MB
Typical Power (No Modules) (Watts): 40
DC Input Current: n/a
Total onboard WAN 10-100-1000 Ports: 2
Rack-Mount 19 in. (48.3 cm) EIA: Optional
AC Input Frequency: 47 to 63 Hz
Double-Wide EHWIC Slots: 2
Service Module Slots: 0
Rack Units: 1 RU
Non-Operating Altitude: 15,000 ft (4,570m)
Maximum End-Point PoE Power Available from AC PoE Power Supply (Watts):130
Maximum Power with AC Power Supply (Watts): 150
The slots and ports of Cisco 2901 router
① EHWIC 0,1,2 and 3 (0, far right) ⑥ USB 0 and 1 (1, top)
② Compact flash 0 and 1 ⑦ AUX
③ USB serial port ⑧ 10/100/1000 Ethernet port (GE 0/0)
④ RJ-45 serial console port ⑨ Ground
⑤ 10/100/1000 Ethernet port (GE 0/1)

3. Cisco 2901 VS Huawei
Vendor Product Description Huawei Advantages
CISCO ISR 2901
Support 35 users and local survival
100 voice mailboxes, concurrent 10
Maximum support 16 FXS / 16 FXO / 8BRI
HUAWEI
eSpace
U1911
U1911 Integrated Host,provide 1 SCU,1
MTU,1 power,including 16 concurrent
voice conference participants license.
Single maximum support 100 users, the integration of highly
integrated gateways, support outgoing PSTN and analog
terminal access, support key board backup and dual-standby,
up to 64 FXS / 24 FXO / 12 E1 / 8 BRI.
Source:http://www.cisco.com/c/en/us/support/routers/2901-integrated-services-router-isr/model.html
From https://howcisco.wordpress.com/