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  1. #1
    Registered User
    Join Date
    Dec 2006

    How usable is VoIP?

    The end customer is interested in the function of the total chain operator - hardware. Below some experience from ten months use of a Nokia E61 with some major European operators. All with the intention to convey information resulting in better software for VoIP.

    The problem is that VoIP is not stable over a longer time period.

    I am using two operators; Freecall belonging to a group called Betamax selling under various brand names, and Sipgate.

    Freecall, just for outgoing calls

    For a long time it worked OK. Since some months nothing happened when trying to call. Occasionally a call was fullfilled but most of the time nothing happened. It turned out that maybe up to 10 minutes after I hung up the other party got the call, when answering nothing in the other end. I was billed for the call.

    In the settings of the E61 there are three choices for the transport protocol; Auto, UDP and TCP and the default setting is Auto. It turned out that changing from Auto to UDP solved the problem. After doing that it works again. Using Auto or UDP doesn' t matter for Sipgate.

    Sipgate, also for incoming calls

    Over these ten months Sipgate has been the most reliable operator. They also have excellent set up instructions, screen dumps from an E61 with my personal settings blended into the pictures. Since some months Sipgate started loosing the registration at the server. It can happen relatively quickly after registering, it can take hours. It happens more often during the time of the day when it is heavy traffic. I am using Freecall and Sipgate simultaneously. Only Sipgate is loosing registration, Freecall never looses registration.

    Loosing registration stops incoming calls of course. In practical life it also stops calling out, it might take several minutes to register again and I do not want to wait several minutes to make a call. In reality it makes the service inoperable.

    I have been looking at the communications between the E61 and the server, all communication is UDP:

    When getting the registration with the server I get a lease for 5 minutes, the time until I have to register again. Just before the end of these 5 minutes the phone initiates a new registration. In the correspondence some packages are exchanged in each direction. Normally a new registration is granted within 0,2 seconds which corresponds to the round trip time to the server. Sometimes I can see that the phone is initiating the process but does not get a reply. The phone continues trying for one or several minutes - I have not been able to catch the process when it looses registration. I do not know after which time the phone is considering the connection dead and closes down. This is what is happening, once the connection is closed the phone doesn't try again. It seems that the problem is due to heavy traffic to/inside the server that gets congested sometimes and the E61 disconnect. I have not found any remedy for this problem. The E61 is treated differently by the server compared to the software client which can be downloaded. When using that a lease for 10 minutes is granted every time.

    The old fashion phone network we are used to was designed to have an availability of 99,999 % or better, called the five nines. Seen over the 10 months I have used VoIP with the E61 I don't think I have one nine even. At least two operators are needed to have one working.

  2. #2
    Registered User
    Join Date
    Jul 2007

    Re: How usable is VoIP?

    I have been using VOIP service since 3-4 months.........its aamazing...

    Last edited by Nokia Ron; 2007-08-01 at 16:13. Reason: inappropriate signature

  3. #3
    Registered User
    Join Date
    Dec 2006

    The reason why Sipgate looses registration?

    I am trying to find the reason for a stochastic error. Due to this I can not claim with 100 % certainty that the analyzes below is correct. However, I am quite certain to be right.


    I am today using two major European VoIP operators which I have been using for about ten months with my Nokia E61. I normally have both of them started. Sipgate has in general worked very well but the last months it looses registration randomly. This prevents incoming calls and, in real life, outgoing calls as it can take several minutes to register again. The problem is concentrated to the times when I assume people are using/connecting their phones. During a normal weekday I estimate that registration is lost at least 10 times between 9 and 12 am, during late afternoon the registration could be kept for hours. The other operator used simultaneously, Freecall, never looses registration.


    Sometimes the Sipgate server is not accessible. The E61 gets a lease for 5 minutes before it has to initiate a registration again. If it can not reach the server with a few attempts it closes the connection and does not try again. A new registration has to be initiated manually.

    I do not have the tools to sniff the wireless connection to the E61 but I have been able to see the E61 making a few attempts and then stopping. During one morning I sniffed the communication between a desktop computer using the software supplied by Sipgate and the server. Between roughly 10 - 12 am the server was not reachable during one period of 27 minutes; longer to be correct, this client gets a lease for 10 minutes meaning that the to get the time the server was not reachable one should add 0 to 10 minutes to the above 27 minutes.

    During these 27 minutes the program made 57 attempts to contact the server and succeeded eventually. Should the situation I see be typical something like that seems necessary. The reason the E61 skips trying should be to save power. In this case this approach doesn't work together with Sipgate.

  4. #4
    Registered User
    Join Date
    Aug 2007

    Re: How usable is VoIP?

    For sending REGISTER S60 SIP stack follows the
    non-INVITE client transaction state machine
    specified in RFC 3261 in chapter 17.1.2

    The differences are that:
    - T1 is 3000ms instead of 500ms
    - T2 is 16000ms instead of 4000ms
    - T4 is 17000ms instead of 5000ms

    In practice this means that S60 SIP implementation tries to resend
    REGISTER with the following intervals for each transaction:
    3s, 6s, 12s, 16s, 16s, ...
    The transaction times out after about 3 minutes.

    After the initial transaction timeouts,
    S60 SIP still tries to recover the registration of an IETF-type of SIP profile
    for about three hours generating new REGISTER transactions
    with an increasing retry interval.
    This interval can be something from some minutes to about half an hour.
    In the worst case if Sipgate is unavailable for 27 minutes,
    S60 SIP registration would succeed after about an hour
    from the moment the unavailability started.

    When the registration recovery is ongoing,
    the SIP profile in SIP settings shows "Not registered".
    If also the registration recovery has failed,
    the SIP profile in SIP settings shows "Registration failed".

  5. #5
    Registered User
    Join Date
    Aug 2007

    Cool Re: How usable is VoIP?


    Dear Sir,

    we would like to deploy VOIP Mobility in a big company where more than 1000 employees are working. Please find below my questions for your kind consideration and action.

    1. We would like to purchase 1000 handsets of Nokia either E61 or E61i, which is recommended by you to use built in voip client?

    2. Where can we find the best and cheapest price for the above-mentioned handsets in the world? Because we would like to buy 1,000 handsets at a time?

    3. AT present we are using Fring application in our organization on all our Nokia 6680 handsets. Is it possible for us to change the name and logo of Fring application and use our own name and logo on their application?

    4. Nokia E61 enterprise device has a built in voip client to configure and use by service providers. We configured the settings to work with sipgate.co.uk service and it's working. But, how to insert our brand name and logo? Because we want to show our company's name and logo instead of others. is it possible?

    5. How to create an SIS. application that configures the Nokia client and send it over the air by sms?

    6.How to create a standalone full duplex VoIP client with Symbian C++ and what are the requirements?

    Your are all humbly and kindly requested to help us in this regard by giving the answers so as to deploy Nokia VOIP Mobility services.

    Please find below my complete address to be contacted:

    MOBILE NO. +919866464059
    E-MAIL ADDRESS: shaikh.bashaa@rediffmail.com

    Thank you and best regards,

  6. #6
    Registered User
    Join Date
    Dec 2006

    Re: How usable is VoIP?

    Thank you for your help!

    The first time it loses registration I get “Registration failed”. After that the indications seems to be erratic.

    I have done some more sniffing, between the Internet and the router. I have not sniffed the wireless connection between the router and the E61. As I understand the results the E61 gets temporarily blind, or blindfolded. Depending on when this happens in the sequence the results are different.

    The typical registration process is REGISTRATION from the E61 followed by a response Unauthorized from the server. Another REGISTRATION followed by an OK from the server. The CSeq is incremented between the two attemps as it shall be.

    Below two cases:

    CASE 1

    The E61 sends a REGISTRATION request and get an Unathorized as response as it should. The next attempt REGISTRATION has the same value for the CSeq. The sequence continues with increasing time intervals 3s, 6s, 12s, 16s, all with the same value for CSeq. When the E61 has made it's 12 attempt it increments the CSeq and get's an OK.

    CASE 2

    Here the E61 does not react on an OK from the server but continues sending new REGISTRATION requests, all with the same value for CSeq and the time sequence as above. The server continues responding to the attempts with an OK until it has sent three OK in total. The next response looks like:

    Result code: 400
    Result string: Bad Request
    Contact: <sip:5001234@;transport=UDP>;expires=579
    P-Registrar-Error: Invalid CSeq number

    The server starts what seems to be an irrevocable count down to close the session for the following attempts as indicated above in Fat and Italic.

    My conclusion from the above is that the E61 doesn't get, or doesn't react, on information now and then for some time. It is temporarily blind or blindfolded. The router has an ALG (Application Layer Gateway) and theoretically the router could cause the above.

    There is also another peculiarity which I doubt can be caused by the router. All the time the E61 is offered a lease time of 600s. Consistently it starts a new registration process after 300s. It handles the offered lease time from other operators in a correct way.

    Until lunch I have been watching the E61 as often as I remember initiating a new registration for Sipgate when it has happened. I have had to re-register about 5 times. I have got one reply stating that they are using Sipgate without losing registration. I would appreciate very much to hear more people using Sipgate with an E61, latest hardware, without losing registration.

  7. #7
    Registered User
    Join Date
    Dec 2006

    My problem is solved

    I am using a D-Link DI-634M router. The solution for me was to turn off the ALGs in the router, Application Layer Gateway. These are functions permitting the use of a number of services without changing the settings in the router. Services like SIP, Messenger and streaming media. The biggest change in the latest firmware for the router was to give the possibility to turn off ALGs individually. This was only possible for some of them. Several, including SIP, could not be turned off.

    I changed back the firmware in the router to the second last firmware AND turned on “Gaming mode”. This function doesn't exist in the latest version and, undocumented, turns off the ALGs. Had to turn off all the ALGs which resulted in services like streaming media not working. Solved this in a simple way; opened the UDP ports 5 004 - 65 535 in the router.

    On D-Links page in France the second last firmware can be found, is called 2.01b3. The latest giving me problems is called 2.01b04

    Technically the problem was caused by the router blocking incoming traffic for shorter and longer periods. Depending on when this started the consequences were different. If it happened just before an “OK” should be received as a reply on a REGISTER request the following happened:

    The E61 didn't receive the OK and sent a new request to register and got another OK. This continued until three OKs had been received. After that the verdict from the server is a code meaning “Syntax error”. The E61 continues making attempts to register, getting the same answer. At the same time an irrevocable process from the server ending in closing the session is started. A new session has to be established manually.

    OK, the server can not be responsible for packets lost in my router but, on the other hand, three packets lost in a row is hardly a syntax error. Normally the server, and the client are very forgiving and tries jointly to pick up the session again. In this case three lost packages during roughly 20 seconds cause the close down.

    Registering could be tricky before, took some time and I might have to wait a while. This for every operator. Now registering happens instantly.

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