Monthly Archives: December 2018

Snom D735 review

I’ve been using Snom Voice over IP telephones for about 10 years. Their software works reliably and provides all the features you might wish for, and the hardware is solid too. I know it’s 2018 and most people don’t use landline phones anymore, but the audio quality is still much better, you can’t comfortably hold a cell phone between your shoulder and your ear, and cellular reception isn’t great where I live.

I started with a 360, then had an 870 and later a 760. When it was time to get a new phone, my list of requirements was pretty short: it should have a USB port on the side for a headset and it should have a graphical display. That left only the D735, D765 and D785. The latter two are priced rather similarly, while the first one can occasionally be picked up for just around 100€.

This article isn’t going to be about the software running on the phones: it is and has always been great. Also, it’s the same across all of Snom’s models. So I’ll just write what I liked and didn’t like about the hardware.

I first tested the D785 for a few days. It’s rather bulky and while the large display looks great, the software doesn’t really make much use of all that extra space (yet). The self-labeling keys with the second display seem like a neat feature, but they are a bit hard to read when the backlight is off and not as useful as I had expected.

So I decided to settle for the D735. The one obvious downside is the tiny screen by comparison to the D765. The entire UI is sized down and even the phone number displayed while in a call scrolls horizontally because its width doesn’t fit. There is still quite a bit of whitespace on the call screen, so if Snom reduced the margins a bit, I think it could actually fit a lot more onto that screen. The downside is also an upside: the phone is smaller, more akin to the D715 than to the D765. While the D765 has two rows of six speed dial keys each above the keypad, the D735 has four of them on either side of the display. That allows it to display labels for them on the screen so you can immediately see what would happen if you pressed them. It also lets you have four pages of different speed dial keys. The labels are very narrow — just showing an icon and a few characters of text. However, they tie in with the proximity sensor. Snom has advertised that as a unique and highly innovative feature, which seems overblown — until you actually try it. Just move your hand close to the phone and it displays the full key label (across half the width of the screen). This allows you to put a lot more text into the label than you could on the paper-labeled keys of the D715 or D765 and even more than on the second screen of the D785.

Personally, I think the D735 has the potential to replace the D715 as Snom’s “default” phone. Supposedly the D715 is their best selling device. Since the D735 only costs a little more and has a color screen and more speed dial keys, it seems like a no-brainer to prefer it over the D715. I can also see it cutting into the D765’s sales a bit — if you don’t mind the smaller screen, you get basically the same feature set in a smaller case. The D785 still remains Snom’s top of the line model — if you want a gorgeous huge screen and self-labeling speed dial keys, it offers a great package. The D735 however may just provide the best value of any of the devices Snom currently has in its lineup.

OpenWRT on AVM Fritz!Box 3370

I was looking for a new DSL modem and router as I am switching from cable to VDSL2. I was eyeing the Ubiquiti EdgeRouter series for a while because they have a big feature set at a reasonable price. I was a bit reluctant about the X series as they seem to be a bit troubled by their small flash memory and the Lite doesn’t have an SFP slot, which would have been nice for the fibre-to-the-home future. Also, both the X and the Lite have been available for quite a few years now, so I’m not sure how long they would have remained in firmware support. The 4 is much more expensive however, and I’d still need a VDSL2 modem, which seems to cost around 100€ (e.g. Draytek Vigor 130 or Allnet ALL-BM200VDSL2V).

Of course, I could have gotten an off-the-shelf router with an integrated modem, like the AVM Fritz!Box series that’s very popular in Germany and probably paid less in total (standalone VDSL2 modems are rather expensive because not many people want/need them). I had a Fritz!Box on cable for the past few years and am not particularly happy with the quality of their firmware though. The hardware is great, however.

So I decided to go with OpenWRT. The only built-in DSL modems it supports are Lantiq chips, so it had to be one from that list. I wanted something that has at least 64 MB of flash memory (so I could install some extra packages) and Gigabit Ethernet on all four ports. Luckily, OpenWRT recently got full support for the AVM Fritz!Box 3370. AVM announced that model back in 2010 and dropped official support for it in 2015, so they are available for ~25€ on eBay nowadays. Other models that would have been nice but are not currently supported by OpenWRT are the 3390 (simultaneous dual-band WiFi), and 3490/7490 (USB 3.0, 802.11ac, 512 MB flash memory and 256 MB RAM; the 7490 additionally has phone ports which can’t be used with OpenWRT). The ZyXEL P-2812HNU-F1 and P-2812HNU-F3 are quite similar to the AVM 3370, but they are not as readily available on eBay and tend to cost about twice as much.

OpenWRT doesn’t provide too much information on how to install, but it’s quite straight-forward. First, you need to check if your device is at least revision 2 and that it doesn’t have a certain bad bootloader version that makes installation more difficult. Go to on the original firmware, log in and click “Support-Daten erstellen”. In the resulting file, you should see something like the following at the top:

HWRevision      175
HWSubRevision   5
ProductID       Fritz_Box_3370
urlader-version 2475

Also, we need to know what kind of flash memory chip the device has. Scroll down to ##### BEGIN SECTION dmesg and look for something like

[ 1.450000] [HSNAND] Hardware-ECC activated
[ 1.450000] NAND device: Manufacturer ID: 0x2c, Chip ID: 0xf1 (Micron NAND 128MiB 3,3V 8-bit)

Download the files corresponding to your flash chip. Set your IP address statically to and reboot the router. When the ethernet interface comes up after a few seconds, ftp and upload the firmware as documented by OpenWRT:

quote USER adam2
quote PASS adam2
quote SETENV linux_fs_start 0
put openwrt-lantiq-xrx200-avm_fritz3370-rev2-micron-squashfs-eva-kernel.bin mtd1
put openwrt-lantiq-xrx200-avm_fritz3370-rev2-micron-squashfs-eva-filesystem.bin mtd0
quote REBOOT

OpenWRT is now ready at after a few minutes.

Note that Fritz!Box 3370 support is not in the 18.06 release version, only in the current snapshot builds. This means that the luci web interface is not pre-installed and you should only install new packages within the first few days after flashing (so you don’t pick up newer packages incompatible with your firmware).

After using the 3370 for a little while, unfortunately I noticed that it doesn’t handle more than around 60 Mbit/s. So be warned that it might not exhaust a 100 Mbit/s down, 50 Mbit/s up line. This seems to be due to a slightly underpowered CPU.