So, the Digium IP phones had been around with us for over a year now, specifically announced at ITExpo 2013. For some odd reason, which is way beyond my personal understanding, these phones aren’t yet popular in Israel and are still being favored for the various Chinese brands. Regardless of that, we’ve received the entire device range for testing and review. We will summarize our findings in two separate blog posts, one related to Integration and one related to Development.

Digium D-70 Under the Scope

There is something somewhat exhilarating in unboxing hardware – regardless of what hardware that is. At first glance, the D-70 is by design aimed at competing with the higher level IP phones on the market. In the same segment, purely from a design perspective, I include the following: Polycom SoundPoint 650/670, Cisco 796X series, SNOM 8XX series, etc. As you may notice, I’m not including Yealink/Grandstream/Fanvil/etc in the list, simply because this phone is by definition not aimed at the “lower price range” of the market – with a retail price standing at 390$ !

Exterior and General Usability

The things I liked:

  • 1. The look and feel are that of a high end Cisco/Polycom type phone
  • 2. The buttons are clearly marked
  • 3. The screens are well lit and easy to read from almost any angle
  • 4. The keys don’t give a rubbery feel to the touch – unlike many other phones


The things I didn’t like:

  • 1. The functional keys are located at the bottom – I would normally expect the redial to be above the keypad, same for hold and transfer
  • 2. The “X” key should be used as an escape key, and it isn’t – naturally I would expect that in a menu pressing “X” would go back – it doesn’t
  • 3. The softkey “Status” is somewhat misleading, it should be labeled as “Do Not Disturb” – in addition, clicking it should result in a large DND avatar, not only a small change in the line keys display


Management Interface

You can say many things about Digium, if there is one thing Digium excels at is learning from their mistakes and providing a nicely built UI and UX. The phones management interface is one of nicest and most inviting I’ve seen in a long time. The interface has a “Mac Style” look and feel, which gives is a very polished look – surpassing almost any IP phone I’ve seen to date.

The interface is composed of a single page, with some background JavaScript communications with the phone. The result is a very fast, very slick interface – which initially gives a similar user experience for the old Sipura/LinkSys phones – before the Cisco buyout.

Upon examining the actual interface source code, I couldn’t find the configured the IP Phone’s SIP account password in the interface, which means it is stored on the phone and the backend application is smart enough not to show it.

The things I liked:

  • 1. The interface is fast and slick, easy to follow without too much technical jargon
  • 2. The configuration is very easy and makes sure you can’t do many mistakes
  • 3. Configuring the background image for the phone is easy and straight forward, which in many cases is a selling point (believe it or not)


The things I didn’t like:

  • 1. Why only HTTP interface? HTTPS interfaces are common and should be the norm as I see it
  • 2. Why am I not able to modify the management port? I should be able to do so
  • 3. Contacts – I should be able to define those in the UI
  • 4. Codecs – Ok, so I’m aware there are some legal issues with incorporating Opus, but I think it should have the option to add additional codecs
  • 5. Ethernet Ports – I should have the ability to choose if I would like to work as a Bridge or as NAT
  • 6. Logging – logging to an external server is awesome, but why only syslog? GELF and other formats are also available as LGPL libs
  • 7. One thing I truly miss is the ability to conduct a SIP capture directly on the phone, SNOMs have it and it is a very useful tool


Security Considerations

  • 1. No Support for TLS – In an ever growing market for secured SIP, adding SIP TLS support to the phone seems a mandatory requirement to me
  • 2. No Support for SRTP – Well, I’m not yet asking for SRTP-DTLS, but at least the already common SRTP-SDES should be available. Yes, not even Polycom has that one nailed down, but I would expect a phone fully support it’s master (when master refers to Asterisk)
  • 3. Default settings are really good, but when configuring the phone for a production system – having the “Accept all calls from any host” as your default is a bad practice. I’ve personally exploited that little mis-setup in almost every IP phone on the market, by sending it a forged SIP packet with SipVicious and generating AIT based traffic 🙂


[edited 06.05.2014]

So, I’ve been using the phone for about 2 weeks now, and I have some additional insights:


Operations and Debugging

If there is one thing that I like about SNOM phones is the ability to capture SIP traffic directly from the phone, download a pcap file and load it into wireshark. This kind of functionality, at least as I see it, is crucial for any IP telephony sysadmin. The primary reason for using something like that is simple – we can’t always have direct access to the network (at least as the switch level), this gives us another pair of eyes into the network and enables us with additional data, that sometimes is crucial to support your system correctly.

Sound Quality

What can I say, Digium truly went all over with making sure the sound quality of the phone is not only good – it is superb!

To an audiophile like myself, who is somewhat sensitive to screeching sounds and crackling speakers, the sound quality of this phone is as good, if not better, than my Polycom 670. The audio is crystal clear and if you are using HD codecs, the HD capable handset really makes a difference.