Compatibility Guide

Compatible Phones

While the OnSIP service supports a broad range of SIP features and functionality, any device which supports and is compliant with the following minimum requirements will work:

• RFC 2833 - RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
• RFC 3261 - SIP: Session Initiation Protocol
• RFC 3263 - Session Initiation Protocol (SIP): Locating SIP Servers
• RFC 3515 - The Session Initiation Protocol (SIP) Refer Method
• RFC 4961 - Symmetric RTP / RTP Control Protocol (RTCP)

Furthermore, we have done successful extended interoperability testing with the following products. Prices are approximate retail pricing.

Best Buy:
Polycom 550 - HD Voice - $246.99
Polycom 301 - $117.99

Other phones we recommend and have tested with MSRP:
Aastra Phones:
Aastra 57i CT IP Phone - $331.99 (includes wireless phone)
Aastra 57i IP Phone - $224.99 (same as above w/o wireless phone)
Aastra 55i IP Phone - $203.99
Aastra 53i IP Phone - $160.99
Aastra 51i Business IP Phone - $119.99

Polycom Phones:
Polycom SoundPoint IP 301 SIP Business VoIP Phone - $117.99
Polycom IP 501 SoundPoint IP Business Phone - $181.99
Polycom IP 550 SoundPoint IP Phone (HD Voice) - $246.99
Polycom IP 601 SoundPoint SIP Business IP Phone - $262.99
Polycom IP 650 Soundpoint IP phone with HDVoice Technology - $299.99

Linksys Phones:
Linksys SPA942 SIP IP Phone With Dual RJ45, PoE - $139.99
Linksys SPA962 Color IP Phone With Dual RJ45, PoE, and Six Line Appearances - $246.99

All of these phones can be purchased at VOIP Supply

Compatible Routers and Firewalls

Generally, we have found that OnSIP works great with all sorts of routers and firewalls so long as:

• Any SIP ALG has been disabled (this is a function on some routers)
• Any SIP firewall has be deactivated (this is a function on some routers)
• No more than a single NAT server is on your internal network

For entry-level routers, we recommend the D-Link DIR-615 Wireless N Router Hardware Version B.

While the list of routers and firewalls known to work is far too long for us to practically maintain, routers from Cisco, Juniper, Linksys, D-Link, Apple and Edgebox among many others are known to work.

Incompatible Hardware and Software

• Netgear Routers
• includes a SIP Application Level Gateway (ALG) which always substitutes the external IP address for any internal IP address in SIP requests. There is apparently no ability to disable the ALG
• gives two different internal devices the same external port on outgoing packets. This prevents the reliable use of more than one SIP device behind the router
• Sonus Networks
• some versions of Sonus applications on some Sonus products have RFC 2833 DTMF interoperability issues with our service