[Users] Re: Re: MediaProxy & PSTN GW

Bogdan-Andrei Iancu bogdan at voice-system.ro
Mon Aug 22 12:32:04 CEST 2005

Hi Ozan, Hi Klaus,

the default IP routing of the UA may be more poor than forcing the 
routing via a additional hop....I encountered couple of times such 
situatations........strange, but may happen :).

Ozan, to force mediaproxy in your script, do so:

 if (uri=~"^sip:0[0-9]*@*") {
     rewritehost("195.XXX.122.XXX");        # This is PSTN Gateways's 
Public IP
     use_media_proxy();      # add this (bogdan)
     t_on_reply("1");        # add this (bogdan)

# add this (bogdan)
onreply_route[1] {

If it works (the relay), let me know if it really improved the QoS - I 
will add your case to my exceptions book ;)


Klaus Darilion wrote:

> That does not help you - inserting another hop can not compensate the 
> bottleneck between the UAs and the Internet (the ADSL connection).
> BTW: 600km is not far away. Which Codec you you use? Try low-babdwidth 
> codecs like G729, ilbc, GSM and G723
> klaus
> Ozan Blotter wrote:
>> Dear Iqbal and Bogdan,
>> That is exactly what i need to improve QoS, because the UAs ADSL
>> connection is not fast enough, 512/128k in general, OpenSER and UA's are
>> located in same city but PSTN GW is nearly 600 km (350 miles nearly) 
>> away
>> from this point. I thought since OpenSER is on a good connection (1Mbit
>> Fiber) and can relay to PSTN faster then UA's themselves.
>> Thanks,
>> Ozan
>> Also in terms of ping times how far is the PSTN gateway, as Bogdan said,
>> media proxy will add even more delay, as for sending pstn via
>> mediaproxy, you could do all yourprocessing, and once ser detects that
>> call must goto PSTN, then do all the NAT checking ...this is a
>> oversimplified view...
>> Iqbal
>> Bogdan-Andrei Iancu wrote:
>>> Hi Ozan,
>>> so, if I get it right, you have a PSTN gw locate far away from the
>>> UAs...and instead of letting the media traffic to do directly between
>>> GW and UAs, you want to insert in the middle a RTP relay (mediaproxy)
>>> in order to improve the QoS, right?
>>> If so, I would say this will not help you -  having a media relay on
>>> your media path leads to QoS degradation due additional delays....
>>> If you still want to go for it....I will take a look on tour script.
>>> regards,
>>> bogdan
>>> Ozan Blotter wrote:
>>>> Dear List,
>>>> At below config. i setted up OpenSER on Public IP and PSTN Gateway is
>>>> again on another Public IP. I use Zyxel Prestige Series 660-HW ADSL
>>>> modems on both client side and note that they have SIP ALG, also i've
>>>> completed port forwarding in each modem, so SIP2SIP call happens
>>>> (voice traffic goes from UA to UA) without need of anything extra as
>>>> STUN or RTP RELAY. But since those are very away from each other if a
>>>> UA needs to call PSTN the voice traffic flows from UA to PSTN and
>>>> that lowers QoS :(
>>>> I would like to activate MediaProxy again but just for one case which
>>>> is PSTN, so whenever a UA needs to call PSTN the voice traffic flows
>>>> like :
>>>> UA (ATA) >>> OpenSER + MediaProxy >>> PSTN
>>>> How can i setup this like above without touching SIP2SIP calls
>>>> between UA's...
>>>> or adding the lines beginning with # these to my existing config is
>>>> enough ?
>>>> Thanks,
>>>> Ozan Blotter

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