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Philips Skypephone VOIP855
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TOPIC: Philips Skypephone VOIP855

Philips Skypephone VOIP855 6 years, 11 months ago #2389

  • YLG80
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Philips Skype Phone VOIP 855, planned obsolescence ?

It appears that Skype has discontinued support for that nicely designed VOIP Phone.
The end result is that we cannot any longer use the Skype function.
The communication is cutoff after about 10 sec due to a missing new audio codec.

Here are comment picked up from community.skypephone.com

Same problem here, but maybe I can give a little more detail...
My VOIP8551B stops the incoming audio after Skype switches to a higher quality audio codec.
This happens after a few seconds into the call if Skype finds the bandwidth of the internet connection to be sufficient to upgrade the codec.
For Skypeout calls this doesn't happen since the codec for landline calls is different.
Still, I have no fix for this codec problem inside the VOIP8551B. A restart of the baseunit doesn't help.

Quick update....
Skype have now confirmed that my Philips VOIP8551 is no longer supported by them.
They recommend me using a device which is supported by Skype, such as a computer, tablet or smartphone.
It's a shame, because the phone is only 3 or 4 years old, and was well designed and handy and CHEAP.

Isn't it time to try to hack that now useless phone except for landline coms?
Last Edit: 6 years, 11 months ago by YLG80.

Re: Philips Skypephone VOIP855 6 years, 11 months ago #2390

  • YLG80
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Opening the device iq not as difficult as it appears.
Remove the screws located on the backside.
Crack open the casing around the gray part.
See picture below.
The picture shows where to insert a screw driver to crack open the box.


Re: Philips Skypephone VOIP855 6 years, 11 months ago #2391

  • YLG80
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Now that the device is open, you will quickly locate a very interesting connector footprint on tha back side oof the PCB.
It shows connections for JTAG and Serial interfaces.


To use the serial interface, you would need to connect a 3.3V serial to RS232 interface and a use a terminal program like Putty.
Putty settings :
Serial option
Select your COM port.
115200 bauds

If your connections are OK you will immediately discover that this device is using an U-Boot bootlader that can be interrupted by
means of hitting a key.
If you let the device completely booting, you will receive information on the hardware (ARM V5) and software used.
(AEM V5 Linux version and Skype client 37 (1.9.174)

I've made a quick capture:

File Attachment:

File Name: bootloader-cmd.txt
File Size: 6 KB

File Attachment:

File Name: full-boot-up-to-skype.txt
File Size: 7 KB

This is where I am today. I don't know the root pw.
Perhaps we could tweak the SILK codec?

Last Edit: 6 years, 11 months ago by YLG80. Reason: serial NONE

Re: Philips Skypephone VOIP855 6 years, 11 months ago #2393

  • YLG80
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Here is how to boot to the kernel.

If your device was powered, disconnect the power supply.
Reconnect the PS and immediately hit Enter until it interrupts the bootloader.
Hit the 5 key to enter into bootloader Firetux command mode.

Once in command mode, enter the following commands

setenv bootargs 'console=ttyS1,115200n8 root=/dev/mtdblock6 rootfstype=jffs2 noalign mem=14M single'

This will bring you to the kernel command mode.
Last Edit: 6 years, 11 months ago by YLG80.

Re: Philips Skypephone VOIP855 6 years, 10 months ago #2394

  • YLG80
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The auto startup script is :

It shows that mount sequence :
mount /proc
mount /tmp
mount /dev/pts
mount /sys
mount -a

... which gives access to the skype directory in /data/software/current/combo/skype ...
... where we can find only the executable skyhost file.

BTW, the subdirectory combo is interesting as it looks that this is the directory updated via OTA. (the update file starts with combo)

The directory /data/software/current/combo contains 3 sub directories : dect, scripts and skype.

The scripts/usr subdirectory contains scripts related to network starting.

Where is the codec ?
Would'nt it be easier to use traffic shaping with tc on eth0 ? TC is available.
This would allow us to reduce the network interface bandwith in order to prevent Skype to switch to the unexisting high performance codec in the VOIP855...
This much simpler than trying to tweak Skyhost.
Last Edit: 6 years, 10 months ago by YLG80.

Re: Philips Skypephone VOIP855 6 years, 10 months ago #2395

  • YLG80
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I've found that interesting script by By Scott Seong on


By chance all commands are available in the PNX8181/VOIP855 board kernel.

Here is Scott's script :
# tc uses the following units when passed as a parameter.
# kbps: Kilobytes per second
# mbps: Megabytes per second
# kbit: Kilobits per second
# mbit: Megabits per second
# bps: Bytes per second
# Amounts of data can be specified in:
# kb or k: Kilobytes
# mb or m: Megabytes
# mbit: Megabits
# kbit: Kilobits
# To get the byte figure from bits, divide the number by 8 bit

# Name of the traffic control command.
# The network interface we're planning on limiting bandwidth.
IF=eth0 # Interface

# Download limit (in mega bits)
[b]DNLD=100kbit[/b] # DOWNLOAD Limit

# Upload limit (in mega bits)
[b]UPLD=100kbit[/b] # UPLOAD Limit

# IP address of the machine we are controlling
[b]IP= [/b] # Host IP

# Filter options for limiting the intended interface.
U32="$TC filter add dev $IF protocol ip parent 1:0 prio 1 u32"
start() {
# We'll use Hierarchical Token Bucket (HTB) to shape bandwidth.
# For detailed configuration options, please consult Linux man
# page.

$TC qdisc add dev $IF root handle 1: htb default 30
$TC class add dev $IF parent 1: classid 1:1 htb rate $DNLD
$TC class add dev $IF parent 1: classid 1:2 htb rate $UPLD
$U32 match ip dst $IP/32 flowid 1:1
$U32 match ip src $IP/32 flowid 1:2
# The first line creates the root qdisc, and the next two lines
# create two child qdisc that are to be used to shape download
# and upload bandwidth.
# The 4th and 5th line creates the filter to match the interface.
# The 'dst' IP address is used to limit download speed, and the
# 'src' IP address is used to limit upload speed.

stop() {
# Stop the bandwidth shaping.
$TC qdisc del dev $IF root
restart() {
# Self-explanatory.
sleep 1
show() {
# Display status of traffic control status.
$TC -s qdisc ls dev $IF
case "$1" in
echo -n "Starting bandwidth shaping: "
echo "done"
echo -n "Stopping bandwidth shaping: "
echo "done"
echo -n "Restarting bandwidth shaping: "
echo "done"
echo "Bandwidth shaping status for $IF:"
echo ""
echo "Usage: tc.bash {start|stop|restart|show}"
exit 0

Credit to Scott Seong

For a basic voice call Skype needs only :

Minimum download/upload speed ----- Recommended download / upload speed
30kbps / 30kbps ------------------- 100kbps / 100kbps
Last Edit: 6 years, 10 months ago by YLG80.

Re: Philips Skypephone VOIP855 6 years, 10 months ago #2396

  • YLG80
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After the server crash, here are some addtional information :

I cannot use tc command succesfully despite of the fact that htb 3.3 is installed.
I receive always RTNETLINK error :
RTNETLINK answers: No such file or directory

RTNETLINK answers: Invalid argument
We have an error talking to the kernel

Is that due to a missing module, like imq ?
tc qdisc show gives this classless qdisc:
# tc qdisc show
qdisc pfifo_fast 0: dev eth0 root bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 multiqueue: on
# tc qdisc change dev eth0 root bfifo
RTNETLINK answers: No such file or directory

However telnetd can be enabled by uncommenting the telnetd line in the /boot/bootmode0.sh script.
mount -o remount,rw /
vi bootmode0.sh

Then remove ## in front of the telnetd command.
Reboot, and you have telnet access to the device.

Or, manually launching udhcpc and telnetd allows the user to connect to the VOIP 855 via telnet.

Please note that I've changed the original unknown root password.

Last Edit: 6 years, 10 months ago by YLG80. Reason: vi

Re: Philips Skypephone VOIP855 6 years, 9 months ago #2397

  • YLG80
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Aaargh, I've erased the file /config/backup.tar.gz by mistake, incorrectly using ftpput.
When swapping the source and destination by error, ftpput overwrites the source file with a file of the same name containing the error message.
Really odd.
So now the backup.tar.gz contains:

Connection closed by foreign host

The correct syntax is obviously this:
ftpput -u [ftp-username] -p [ftp-password] [host-address] [destination path and file name] [source file name]

If someone landing over here could extract that file, save it and send it to me, it would be great.
This is the backup used to restore the system in case of failure or wrong ota update.
So right now, I've no longer any parachute against bricking the device other than a full binary backup made under u-boot.
Thanks in advance.
Last Edit: 6 years, 9 months ago by YLG80.

Re: Philips Skypephone VOIP855 6 years, 9 months ago #2399

  • YLG80
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OK, I have to help myself to recover my overwritten file !
So I've decided to use my full night hex dump backup made @ 9600 bauds to be sure that there was no data corruption.
The only partition to restore is mtd4 or /config

Here are the partitions addresses:
[17179569.480000] RedBoot partition parsing not available
[17179569.484000] Using physmap partition information
[17179569.488000] Creating 8 MTD partitions on "physmap-flash.0":
[17179569.492000] 0x00000000-0x00060000 : "U-Boot Bootloader"
[17179569.496000] 0x00060000-0x00080000 : "U-Boot Environment"
[17179569.504000] 0x00080000-0x00200000 : "kernel"
[17179569.508000] 0x00200000-0x00220000 : "macaddr"
[17179569.512000] 0x00220000-0x004a0000 : "config" <-- PARTITION TO BE RESTORED THAT CONTAINS backup.tar.gz
[17179569.520000] 0x004a0000-0x00b00000 : "data"
[17179569.524000] 0x00b00000-0x00fe0000 : "rootfs"
[17179569.528000] 0x00fe0000-0x01000000 : "mode"

mounts as follows:
# mount
rootfs on / type rootfs (rw)
/dev/root on / type jffs2 (ro)
none on /proc type proc (rw)
none on /tmp type tmpfs (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
none on /sys type sysfs (rw)
/dev/mtdblock5 on /data type jffs2 (rw)
/dev/mtdblock4 on /config type jffs2 (rw) <-- this is the partition to restore.

1- Extract mtd4 from the hex dump. The partition starts @ 0x80220000 with 0x27FFFF bytes ending up to 0x8049FFFF.
2- Convert it to binary using sfk v172 (python hexdump 3.1 is way too slow !)
sfk filter mtd4-part.hex +hextobin mtd4be32.bin

3- Verify the binary file (size and content).
Ooops, "VOIP 855, we have problem" !
The ascii dump does not show exactly the same content as the original hex dump. Bytes are looking swapped in the new binary ascii dump.
I did not realize that the ARMv5 CPU is using BE-32 endianness.
I had to swap bytes (32 bits) in the original hex dump prior to convert it into binary.
Now it's OK.
4- Time to upload the binary into the VOIP 855 board:
The upload has to be done at a free RAM address which is above 0x20800000 RAM.
I've used the kermit protocol with tera term to upload the binary file at the default baud rate (19200 bauds)that I use to debug.
loadb 20800000

It takes about 25 minutes to upload the binary file
Then a quick check to verify if the memory dump shows exactly the same data as in the backup, at least at start and end.

Before progamming the flash, we must erase the sectors that will be reprogammed.
The area to be erased MUST start en end with a flash sector. (to be found with flinfo under u-boot)
erase 80220000 8049FFFF

Once erased, we can eventually restore the original mtd4 partition with cp.b
The cp command automatically detect if we are programming a flash chip and uses the appropriate flashing algorithm.
cp.b 28000000 80220000 27FFFF

The flash chip is rather quickly reprogrammed and the process can be followed via the console :
firetux # cp.b 20800000 80220000 27FFFF
Copy to Flash... 36....35....34....33....32....31....30....29....28....27....26....25....24....23....22....21....20....19....18....17....16....15....14....13....12....11....10....9....8....7....6....5....4....3....2....1....done

That's it.
Reboot the VOIP 855 and during the boot there was no /config mounting error.

Here is the original VOIP 855 restore file:

File Attachment:

File Name: backup.tar.gz
File Size: 1,741 KB
Last Edit: 6 years, 8 months ago by YLG80.
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