The ability to dial by SIP URI is a big advantage if you truly want to make the most of wideband calling. SIP is, well…y’know…SIP…the protocol at the root of most IP telephony. And URI means “Uniform Resource Indicator.” It’s a form of an address not unlike an email address. For example, sip:email@example.com is a SIP URI that rings the Polycom phone on my desk.
Go ahead and call it if you can, I don’t mind. If I’m not there you’ll get my voicemail.
Soft phones make it easy to dial by SIP URI since you’re already using a computer, so you have ready access to a keyboard. Traditional phones, lacking a full keyboard, don’t offer such convenience. Most business class phones will store SIP URIs in the phones contact directory (see below). As a practical matter this can be enough for most people, given that its also easy to store the URI arising from incoming caller ID into your contact list.
The big deal about dialing by SIP URI is that it spans service providers. Unlike Skype, where you can only call other Skype users via wideband, using Gizmo5 you can call any SIP URI…including users of other SIP services, like my OnSIP account. And all calls to/from SIP URI using Gizmo5 are free.
Incidentally, the Gizmo5 soft phone does not support G.722. This is a bit of a drag since most business grade IP phones support G.722 wideband calling. All the newer, CATiq certified cordless phones, like the Gigaset A580IP and S675IP, also support wideband calling using G.722.
You might wonder why I dwell on the G.722 so much. I think that it’s really important that we have interoperability between different devices and services. At the moment G.722 is the lowest-common-denominator of wideband codecs. It’s not ideal, but it’s more widespread than just about anything else, so for now so it’s what I prefer to use.
One of the advantages of Gizmo5 is that they let you bring your own SIP compliant software or hardware IP phones into the mix. This alters scope of possibilities considerably.
There’s nothing to stop you from using another SIP soft phone to access your Gizmo5 account. I recommend the latest version of Eyebeam for Windows and PhonerLite (shown above) as both are G.722 wideband capable, the later being freeware.
Taking a step beyond soft phones you might choose to use wideband capable hardware IP phones. Only the newer models are wideband capable. If you, and the person at the other end have wonderful Polycom SoundPoint IP550s or IP450s, then your call will be placed using G.722..in glorious wideband.
However, if you have the IP450 and the other person an older IP600, then the best codec that the two devices have in common is G.711…and a narrowband call will ensue.
It’s worth noting that even a narrowband call placed over a pure IP network, like between Gizmo5 accounts, will sound better than a call placed via the PSTN. This is because the call path is more direct, and high quality IP phones tend to have great hardware properties. That is, the speakers and the microphones are better quality. This alone can make a big difference, even in narrowband.
You can dial normal phones from your Gizmo5 account. To dial PSTN numbers you must invest in some Gizmo5 credits. Like Skype, calling the PSTN from Gizmo5 is cheap but not free. Since the calls are being routed to the PSTN they will be negotiated down to G.711 narrowband in the best case.
This ability to use a diversity of hardware or software phones with Gizmo5 means that you never really know what the other person might be using to take your call. Thus you cannot ensure that your calls to everyone will be wideband. The best that you can do is leverage wideband automatically whenever possible.
Of course, if you have a wideband capable phone of any description then you might want to join in on a VoIP Users Conference call one Friday. We use the ZipDX wideband conference service which is available via SIP URI. See http://vuc.me for details.