Tag: VoIP

Should anyone ask, I am spending more time on the phone

I was just checking out my network’s traffic prioritization this morning and realised I spent most of yesterday on the phone. VOIP traffic is marked as red on the graph:

Most of these are also international calls from my mobile phone. My monthly phone bill comes in at around 30€. (rental, some SMSs, 100 minutes and 10€ for internet access).

I’ve setup my mobile to, by default, make all calls via VOIP. These calls then go out via the cheapest provider for each route. The simplest of which are my family calls. Extension 103 reaches my mother in Chelmsford, 106, my sister in Scotland and, 108 my brother in South Korea. Other calls are then sent either via a VoipCheap trunk or through a Truphone trunk that I have terminated on my VOIP server.

For inbound calls, I have the following numbers that will reach me, where ever I am:

US: +1 425 906 3145
UK: +44 20 7043 6756
Germany: +49 894 2095 5854

I went through a lot of teething pain at the start setting everything up but, after a year or so, things just work. At some point I’d like to add ENUM peering to the setup so that voip nodes stay voip nodes and voice traffic never touches the legacy PSTN.

Should anyone ask, I am spending more time on the phone

I was just checking out my network’s traffic prioritization this morning and realised I spent most of yesterday on the phone. VOIP traffic is marked as red on the graph:

Most of these are also international calls from my mobile phone. My monthly phone bill comes in at around 30€. (rental, some SMSs, 100 minutes and 10€ for internet access).

I’ve setup my mobile to, by default, make all calls via VOIP. These calls then go out via the cheapest provider for each route. The simplest of which are my family calls. Extension 103 reaches my mother in Chelmsford, 106, my sister in Scotland and, 108 my brother in South Korea. Other calls are then sent either via a VoipCheap trunk or through a Truphone trunk that I have terminated on my VOIP server.

For inbound calls, I have the following numbers that will reach me, where ever I am:

US: +1 425 906 3145
UK: +44 20 7043 6756
Germany: +49 894 2095 5854

I went through a lot of teething pain at the start setting everything up but, after a year or so, things just work. At some point I’d like to add ENUM peering to the setup so that voip nodes stay voip nodes and voice traffic never touches the legacy PSTN.

Should anyone ask, I wish I also had the JesusPhone.

OK, I promise this is the last Apple iPhone post for awhile but really this phone is getting way too much press. Perhaps they don’t have phones in the US that people are making such a fuss over it. Listen to this  Apple guy rave about the iPhone.  It’s like he has never seen  anything better than the Motorola StarTAC.

  • It syncs your contacts!  I wish I could do this.  I print out all my contacts and manually type them in. Multiple times per day.
  • You can read your email on it.  I guess you have to be on the interweb for that to work.  I wish my AOL mail account could get Internet email too.
  • Listen to music.  Better than carrying a boombox.
  • Has voicemail – imagine that!  No longer do you need to answer the phone.
  • Did I mention you can look at pictures on it?

Wow – I wish I had a phone that could do all this.  Oh wait, I do, it’s out now and I don’t have to push Apple FanBoysTM aside to look at it. And it does a whole lot more, is an open platform and can call via the internet.I do like apple kit, but I think that Steve has gone overboard with his publicity of the basic features. It’s starting to backfire for him.

Here’s the CBS video. Remember think Motorola StarTAC.

Should anyone ask, I wish I also had the JesusPhone.

OK, I promise this is the last Apple iPhone post for awhile but really this phone is getting way too much press. Perhaps they don’t have phones in the US that people are making such a fuss over it. Listen to this  Apple guy rave about the iPhone.  It’s like he has never seen  anything better than the Motorola StarTAC.

  • It syncs your contacts!  I wish I could do this.  I print out all my contacts and manually type them in. Multiple times per day.
  • You can read your email on it.  I guess you have to be on the interweb for that to work.  I wish my AOL mail account could get Internet email too.
  • Listen to music.  Better than carrying a boombox.
  • Has voicemail – imagine that!  No longer do you need to answer the phone.
  • Did I mention you can look at pictures on it?

Wow – I wish I had a phone that could do all this.  Oh wait, I do, it’s out now and I don’t have to push Apple FanBoysTM aside to look at it. And it does a whole lot more, is an open platform and can call via the internet.I do like apple kit, but I think that Steve has gone overboard with his publicity of the basic features. It’s starting to backfire for him.

Here’s the CBS video. Remember think Motorola StarTAC.

Should anyone ask, I have been reading the international dialing codes

The process of dialing a number and a telephone ringing on the other side of the world is very intersting.  To me at least.  It gets even more interesting when you think about how things like how to bill the call. The whole process is called ENUM.

I learnt some interesting things about the international country codes:

  • Antartica has no country code instead you have to dial the country code of the particular base you wish to speak with
  • The Vatican City has it’s own country code, but instead uses Rome dialing codes
  • country codes  90 to 99 used to be used for intercontinental traffic before 1960

I started reading about this because I followed a link from the E.164 page.  I like e.164 because it maps my telephone number to an ip address that can be looked up in dns.    So if you call me on my VOIP number from your VOIP provider the call is mapped to an ip addresses and never touches the PSTN.

Should anyone ask, I have been reading the international dialing codes

The process of dialing a number and a telephone ringing on the other side of the world is very intersting.  To me at least.  It gets even more interesting when you think about how things like how to bill the call. The whole process is called ENUM.

I learnt some interesting things about the international country codes:

  • Antartica has no country code instead you have to dial the country code of the particular base you wish to speak with
  • The Vatican City has it’s own country code, but instead uses Rome dialing codes
  • country codes  90 to 99 used to be used for intercontinental traffic before 1960

I started reading about this because I followed a link from the E.164 page.  I like e.164 because it maps my telephone number to an ip address that can be looked up in dns.    So if you call me on my VOIP number from your VOIP provider the call is mapped to an ip addresses and never touches the PSTN.

In case anyone asks, my new telco is PowerClean and linksys

When I was out in the center of town today and made 2 international phone calls through wifi access points named PowerClean and linksys. I would have perhaps paid ePlus €10 for the 2 calls, but instead I paid 0¢ when calling via my own Asterisk server and out to the PSTN via Voip Discount. Eplus needn’t worry, I’ll keep paying my rip off subscription to them a little longer. All this is possible using the Nokia E61 which I can highly recommend as a phone.

In case anyone asks, my new telco is PowerClean and linksys

When I was out in the center of town today and made 2 international phone calls through wifi access points named PowerClean and linksys. I would have perhaps paid ePlus €10 for the 2 calls, but instead I paid 0¢ when calling via my own Asterisk server and out to the PSTN via Voip Discount. Eplus needn’t worry, I’ll keep paying my rip off subscription to them a little longer. All this is possible using the Nokia E61 which I can highly recommend as a phone.

VoIP debugging

I have been fighting againt a problem with my VoIP calling setup. The problem presented itself last week and was not accompanied by any software upgrades or network changes on my end. I should first explain a little about my current setup. I use Asterisk as a software PBX. This handles outbound and inbound calls, voicemail and termniation of my London and German and US telephone numbers. Last week I noticed that when I made outbound calls via SipDiscount I would receive no ringing signal and also the call would never be fully setup.

Or so I though. After looking through my logs I discovered that the calls were actually being setup. At first I though that SipDiscount had changed their supported codecs. After searching on the internet it seemed that nobody really knew which were supported codecs. So I setup a list of all codecs that I could support and relied on the SIP negotiation phase to choose the correct one. Unfortunately the symptoms persisted.

On a hunch I then started tcpdumping and analysing the traffic on port 5060 (the SIP signalling port). All this seemed fine too. I saw a common codec being selected and the call setup and tear down completing without a problem.

I banged my head more and then decided to double check my firewall log. This seemed unnecessary since my VoIP calls had all been completing fine for the last year.

Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=693 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180
Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=694 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180
Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=695 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180
Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=696 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180

That seemed odd since my firewall script read:

iptables -A INPUT    -p udp -s 0.0.0.0/0 -d $VOIPIP --dport 10000:20000  -j accept-log
iptables -A OUTPUT -p udp -s $VOIPIP -d 0.0.0.0/0 --dport 10000:20000  -j accept-log

Hmmm. What had happened is that SipDiscount changed their reception port range to something outside the normal range for SIP calls. Normal SIP port ranges are 10000-20000. A quick change of my rules fixed the problem and I now have telephone calls with audio.

iptables -A INPUT    -p udp -s 0.0.0.0/0 -d $VOIPIP --dport 10000:20000  -j accept-log
iptables -A OUTPUT -p udp -s $VOIPIP -d 0.0.0.0/0 --sport 10000:20000  -j accept-log

VoIP debugging

I have been fighting againt a problem with my VoIP calling setup. The problem presented itself last week and was not accompanied by any software upgrades or network changes on my end. I should first explain a little about my current setup. I use Asterisk as a software PBX. This handles outbound and inbound calls, voicemail and termniation of my London and German and US telephone numbers. Last week I noticed that when I made outbound calls via SipDiscount I would receive no ringing signal and also the call would never be fully setup.

Or so I though. After looking through my logs I discovered that the calls were actually being setup. At first I though that SipDiscount had changed their supported codecs. After searching on the internet it seemed that nobody really knew which were supported codecs. So I setup a list of all codecs that I could support and relied on the SIP negotiation phase to choose the correct one. Unfortunately the symptoms persisted.

On a hunch I then started tcpdumping and analysing the traffic on port 5060 (the SIP signalling port). All this seemed fine too. I saw a common codec being selected and the call setup and tear down completing without a problem.

I banged my head more and then decided to double check my firewall log. This seemed unnecessary since my VoIP calls had all been completing fine for the last year.

Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=693 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180
Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=694 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180
Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=695 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180
Mar  1 19:07:15 bunker DENY2: IN= OUT=ppp0 MAC= xsrc=62.245.233.186 DST=194.120.0.163 LEN=200 TOS=10 PREC=0x00 TTL=64 ID=696 DF PROTO=UDP SPT=17820 DPT=57344 LEN=180

That seemed odd since my firewall script read:

iptables -A INPUT    -p udp -s 0.0.0.0/0 -d $VOIPIP --dport 10000:20000  -j accept-log
iptables -A OUTPUT -p udp -s $VOIPIP -d 0.0.0.0/0 --dport 10000:20000  -j accept-log

Hmmm. What had happened is that SipDiscount changed their reception port range to something outside the normal range for SIP calls. Normal SIP port ranges are 10000-20000. A quick change of my rules fixed the problem and I now have telephone calls with audio.

iptables -A INPUT    -p udp -s 0.0.0.0/0 -d $VOIPIP --dport 10000:20000  -j accept-log
iptables -A OUTPUT -p udp -s $VOIPIP -d 0.0.0.0/0 --sport 10000:20000  -j accept-log