Compatibility Guide
Recommended Phones and Routers can be found in our Purchasing 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:
SIP RFC Support
- 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 3264 - An Offer/Answer Model with the Session Description Protocol
- RFC 3515 - The Session Initiation Protocol (SIP) Refer Method
- RFC 4961 - Symmetric RTP / RTP Control Protocol (RTCP)
Please see Phone Configuration for phone configuration options.
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)
- Phones are located behind a single NAT server on your internal network
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 well.
Incompatible Hardware and Software
Incompatible hardware and software is that which tries to change the packet information but does so incorrectly. Many router manufacturers for instance have implemented what are known as SIP ALGs, application level gateways, that attempt to rewrite the SIP packets in order to traverse NATs. Unfortunately these companies are not experts in SIP and implement these gateways incorrectly.
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
DLink Routers (3.x firmware)
- includes a SIP Application Level Gateway (ALG) which always substitutes the external IP address for any internal IP address in SIP requests. Disabling the ALG drops all SIP packets
Sonus Networks
- some versions of Sonus applications on some Sonus products have RFC 2833 DTMF interoperability issues with our service
Unidata Phones
- these phones have multiple SIP RFC violations. Please see our Unidata knowledgebase pages for more information.
