Multiple SIP Clients?

Discussion in 'UK VOIP' started by Anthony R. Gold, Jun 25, 2011.

  1. Can one have a SIP incoming call ring in multiple places and over multiple
    ATAs and softphones such that the first one to pick-up will seize the call?
    My present configurations have each client registering with the server and so
    causing a pre-existing registration to be closed and ended.
    Anthony R. Gold, Jun 25, 2011
    #1
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  2. Anthony R. Gold wrote:
    > Can one have a SIP incoming call ring in multiple places and over multiple
    > ATAs and softphones such that the first one to pick-up will seize the call?


    Yes, that is a standard part of SIP, and implementable at the proxy
    level; it is called branching. It may not be a service operated by
    public PSTN gateways, though.

    > My present configurations have each client registering with the server and so
    > causing a pre-existing registration to be closed and ended.


    I'm not sure that multiple registrations against the same address of
    record is allowed though. Asterisk certainly doesn't support it. You
    would probably have to make to do some hard configuration in the proxy
    or B2BUA. For Asterisk (a B2BUA) you put
    ......Dial(SIP/address1&SIP/address2&SIP/address3&otherprotocol/address4)
    in extensions.conf, or the "dialplan" database.

    One key to this is maintaining the distinction between directory numbers
    (Asterisk extensions) and equipment numbers (Asterisk devices), which is
    often confused when the switching equipment allows similar names for both.
    David Woolley, Jun 25, 2011
    #2
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  3. Anthony R. Gold wrote:
    > Re: Multiple SIP Clients?


    You actually meant servers. SIP user agents act as protocol servers for
    incoming calls.
    David Woolley, Jun 25, 2011
    #3
  4. On Sat, 25 Jun 2011 11:24 +0100 (BST), d (Paul
    Cummins) wrote:

    > In article <>,
    > (Anthony R. Gold) wrote:
    >
    >> *From:* "Anthony R. Gold" <>
    >> *Date:* Sat, 25 Jun 2011 10:44:56 +0100
    >>
    >> Can one have a SIP incoming call ring in multiple places and over
    >> multiple
    >> ATAs and softphones such that the first one to pick-up will seize
    >> the call?

    >
    > Yes. My Sipgate rings my cellphone sip client, my home phone and, if connected, my
    > office Sip phone.


    Many thanks. I had only tried that with VOIPCheap and it had not worked. But
    just I tried it on sipgate and indeed both my ATA and my softphone rang
    simultaneously. That's fantastic to a novice like me. Is there any limit on
    the number of user agents or devices that can be connected and ring? (Thanks
    to David for correcting my error between what is a client and a server.)

    Was my problem with VOIPCheap a matter of setting that I could overcome or is
    this a difference in capabilities between VOIPCheap/Betamax and sipgate?

    > The answerphone at home kicks in after 45 seconds.


    Is that because of a setting of an answerphone on the ringing home phone line
    or is there a sipgate feature that can forward unanswered calls to a
    different account or device or phone number?
    Anthony R. Gold, Jun 25, 2011
    #4
  5. On Sun, 26 Jun 2011 19:06:51 +0100, "R. Mark Clayton"
    <> wrote:

    >
    > "David Woolley" <> wrote in message
    > news:iu4ccp$r5j$...
    >> Anthony R. Gold wrote:
    >>> Can one have a SIP incoming call ring in multiple places and over
    >>> multiple
    >>> ATAs and softphones such that the first one to pick-up will seize the
    >>> call?

    >>
    >> Yes, that is a standard part of SIP, and implementable at the proxy level;
    >> it is called branching. It may not be a service operated by public PSTN
    >> gateways, though.

    >
    > Voipfone claim to be working on it, but not sorted yet AFAIK.


    Does anyone know about VOIPCheap, with whom I was having that problem? After
    Paul mentioned his experience I was then successful with sipgate.

    New question: is there any limit to the number of SIP devices or softphones
    that may be connected to one home LAN? Is it useful for different ones be set
    to different UDP port numbers? And if so, what is the range of port numbers
    that are generally accepted?
    Anthony R. Gold, Jun 26, 2011
    #5
  6. In article <>,
    Anthony R. Gold <> wrote:

    >New question: is there any limit to the number of SIP devices or softphones
    >that may be connected to one home LAN? Is it useful for different ones be set
    >to different UDP port numbers? And if so, what is the range of port numbers
    >that are generally accepted?


    Within reason, no... However who knows what a reasonable limit is.

    Factors that will affect it include the size of the ARP table in your
    router and the MAC to port addressing tables in your Ethernet switches.
    Also your routers ability to manage NAT sessions too. (And routers with
    broken SIP ALGs that are really only expecting one SIP device)

    Then there's the DHCP server and your LAN subnet - once you get over
    254 devices on one LAN you need a bigger subnet.

    Your router doing NAT should give each device it's own outgoing port
    number - which is one way NAT uses to map incoming connections to
    a device, so you really shouldn't have to fiddle with SIP phones at
    that level. (And if you don't have NAT, then there's even less issues)

    So basically it's your router and to a lesser extent Ethernet switches
    that's going to be the limiting factor.

    Gordon
    Gordon Henderson, Jun 27, 2011
    #6
  7. Anthony R. Gold wrote:

    >New question: is there any limit to the number of SIP devices or softphones
    >that may be connected to one home LAN? Is it useful for different ones be set
    >to different UDP port numbers? And if so, what is the range of port numbers
    >that are generally accepted?


    If you are operating a home LAN anyway, you may well find it more
    convenient to set up an Asterisk server to be the gateway between your
    SIP devices and the external SIP provider. That way you can arrange
    multi-rings and so on purely on your own terms.

    Roger
    Roger Burton West, Jun 27, 2011
    #7
  8. On Sat, 25 Jun 2011 10:44:56 +0100, "Anthony R. Gold"
    <> wrote:

    > Can one have a SIP incoming call ring in multiple places and over multiple
    > ATAs and softphones such that the first one to pick-up will seize the call?
    > My present configurations have each client registering with the server and so
    > causing a pre-existing registration to be closed and ended.


    What equipment is suitable for receiving incoming calls from multiple service
    providers? My Linksys ATA, the SPA3102, appears capable of sending calls out
    through 4 different SIP service providers as <gw1> through <gw4> but it
    appears able only to register with one SIP proxy for incoming calls. Is that
    correct?

    I found a softphone (SJphone from SJ Labs) that is able to sit waiting for
    incoming calls from multiple service providers but I am unsure what ATA or
    SIP Phones have that same capability, and I am even unsure what key words I
    should be looking for in descriptions or specifications to find that ability.
    Thanks for any advice.
    Anthony R. Gold, Jul 4, 2011
    #8
  9. Anthony R. Gold wrote:

    >What equipment is suitable for receiving incoming calls from multiple service
    >providers?


    <broken record>

    Don't use an appliance, use a proper computer as your proxy. Asterisk
    and its open-source competition can all trivially do what's needed, and
    forward calls to your actual SIP devices.
    Roger Burton West, Jul 4, 2011
    #9
  10. On Mon, 4 Jul 2011 10:00:54 +0000 (UTC), Roger Burton West
    <> wrote:

    > Anthony R. Gold wrote:
    >
    >> What equipment is suitable for receiving incoming calls from multiple service
    >> providers?

    >
    > Don't use an appliance, use a proper computer as your proxy. Asterisk
    > and its open-source competition can all trivially do what's needed, and
    > forward calls to your actual SIP devices.


    I believe would be neither suitable nor safe. I travel a great deal and, even
    if I was willing to learn enough to install and configure such I system, I
    could never allow all of my incoming phone calls to depend on the good
    behaviour of a PC and its Internet access when those are installed many
    thousands of miles away. I might consider using a hosted service, but I hope
    that will not be necessary for my very simple needs. An appliance will be
    just fine thanks.
    Anthony R. Gold, Jul 4, 2011
    #10
  11. In article <>,
    Anthony R. Gold <> wrote:
    >On Mon, 4 Jul 2011 10:00:54 +0000 (UTC), Roger Burton West
    ><> wrote:
    >
    >> Anthony R. Gold wrote:
    >>
    >>> What equipment is suitable for receiving incoming calls from multiple service
    >>> providers?

    >>
    >> Don't use an appliance, use a proper computer as your proxy. Asterisk
    >> and its open-source competition can all trivially do what's needed, and
    >> forward calls to your actual SIP devices.

    >
    >I believe would be neither suitable nor safe. I travel a great deal and, even
    >if I was willing to learn enough to install and configure such I system, I
    >could never allow all of my incoming phone calls to depend on the good
    >behaviour of a PC and its Internet access when those are installed many
    >thousands of miles away. I might consider using a hosted service, but I hope
    >that will not be necessary for my very simple needs. An appliance will be
    >just fine thanks.


    So what do you call a small box, fanless, diskless, that boots Linux
    and runs Asterisk... I call them appliances ;-)

    They should be no less (or more) reliable than a modern router - which
    these days often runs Linux too...

    The "iffy" bit is more like the ADSL line you put them behind. Mines
    just been offline for 4 days due to BTs incompetence )-:

    Gordon
    Gordon Henderson, Jul 4, 2011
    #11
  12. Anthony R. Gold

    Roger Guest

    On 04/07/2011 11:21, Anthony R. Gold wrote:
    > On Mon, 4 Jul 2011 10:00:54 +0000 (UTC), Roger Burton West
    > <> wrote:
    >
    >> Anthony R. Gold wrote:
    >>
    >>> What equipment is suitable for receiving incoming calls from multiple service
    >>> providers?

    >>
    >> Don't use an appliance, use a proper computer as your proxy. Asterisk
    >> and its open-source competition can all trivially do what's needed, and
    >> forward calls to your actual SIP devices.

    >
    > I believe would be neither suitable nor safe. I travel a great deal and, even
    > if I was willing to learn enough to install and configure such I system, I
    > could never allow all of my incoming phone calls to depend on the good
    > behaviour of a PC and its Internet access when those are installed many
    > thousands of miles away. I might consider using a hosted service, but I hope
    > that will not be necessary for my very simple needs. An appliance will be
    > just fine thanks.

    Anthony
    I ditched my SPA3102 because of the echo issues and bought a Fritzbox -
    best move I ever made regarding VOIP - its simple to set up and can
    register 6 (I think - I've got 3 set up at the moment) different
    accounts plus the landline. You set up one as the default (landline or
    one of the VOIP accounts) and can set up simple dialling rules for
    chosing providers e.g. all calls starting 07 go via the best VOIP
    provider for mobiles. You can also dial an access number to use a
    particular account. A call into any account will make the phones ring if
    its configured to (you can also specify certain accounts not to ring the
    phones)

    Dial plans and config arent as detailed as the SPAs but to be honest I
    think they went a bit too far anyway.

    I still use an SPA1001 as well which does have 2 accounts registered to
    it on one phone.Not sure if you can still buy these or not.
    Roger.
    Roger, Jul 4, 2011
    #12
  13. On Mon, 04 Jul 2011 21:40:45 +0100, Roger <> wrote:

    > I ditched my SPA3102 because of the echo issues and bought a Fritzbox -
    > best move I ever made regarding VOIP - its simple to set up and can
    > register 6 (I think - I've got 3 set up at the moment) different
    > accounts plus the landline. You set up one as the default (landline or
    > one of the VOIP accounts) and can set up simple dialling rules for
    > chosing providers e.g. all calls starting 07 go via the best VOIP
    > provider for mobiles. You can also dial an access number to use a
    > particular account. A call into any account will make the phones ring if
    > its configured to (you can also specify certain accounts not to ring the
    > phones)
    >
    > Dial plans and config arent as detailed as the SPAs but to be honest I
    > think they went a bit too far anyway.
    >
    > I still use an SPA1001 as well which does have 2 accounts registered to
    > it on one phone.Not sure if you can still buy these or not.


    Thanks Roger.

    I'd not heard about echo problems with SPA3102 and I've not experienced any
    such problems myself. My device is using software v3.3.6. I see on the Cisco
    site both this one and also one called v5.1.10 and I do not know the
    differences between them http://tinyurl.com/5tdfqj6 but the lower number
    appears to have the later date.

    My question is not about being able to dial out through a number of proxy
    servers using dialing rules but about receiving incoming calls from multiple
    service providers. The only hardware device with which I have any knowledge
    is this SPA3102 and so I know I could solve my problem with an array of
    these, using one per incoming provider/phone number. But I am looking for a
    device that can be simultaneously registered with a number of providers and
    will ring if and when an incoming call is offered by any of them. Does the
    SPA1001 accept calls from two providers simultaneously, and does the Fritzbox
    do the same from even more?

    I'm fumbling over the terms because I do not know how this capability of
    being register, alert and available to accept incoming calls is named or
    described by equipment vendors.
    Anthony R. Gold, Jul 4, 2011
    #13
  14. On Mon, 4 Jul 2011 22:11:26 +0100, "Graham." <> wrote:

    > I've lost track of what's been discussed in the two current threads but I just
    > want to check that you haven't overlooked a solution that requires nether
    > additional hardware nor services.
    > I have just refined my arrangement slightly and tested the following, so I know it works.
    >
    > My ATA only handles a single SIP account (OK it's a PAP2 so it handles two,
    > but the second account is for all intents and purposes a separate ATA with a separate phone).


    So the PAP2 will work with two simultaneous incoming services? Great! I
    believe what I am looking for is something similar but scaled ever further to
    perhaps 4 or 5 ATAs and perhaps with separate phones or shared phones.

    > The account details are for Betamax, smartvoip.com. My outgoing calls go via this service.
    >
    > Incoming calls are via ukddi.com I have a block of ten consecutive 0161 numbers one (or more if I want)
    > points to my phone with a URI constructed thus:
    >
    >
    > Other varients also work
    > smartvoip_account_name@my_ip_address
    >
    > or, as my IP changes once in a while
    > smartvoip_account_name@my_dyndns_name.dyndns.org
    >
    > I also have a Washington State number from IPKall that does the same thing.


    That was not clear to me.

    Okay on receiving calls to the 0161 numbers from smartvoip, and I presume
    those come through half of your PAP2. But how are you receiving the calls
    made to the IPKall number? Will IPKall also direct their calls to that same
    smartvoip account and server? And if you also wanted to receive calls on
    VOIPCheap and sipgate numbers, how could you handle them?
    Anthony R. Gold, Jul 4, 2011
    #14
  15. Anthony R. Gold

    Bob Eager Guest

    On Mon, 04 Jul 2011 22:55:47 +0100, Anthony R. Gold wrote:

    > My question is not about being able to dial out through a number of
    > proxy servers using dialing rules but about receiving incoming calls
    > from multiple service providers. The only hardware device with which I
    > have any knowledge is this SPA3102 and so I know I could solve my
    > problem with an array of these, using one per incoming provider/phone
    > number. But I am looking for a device that can be simultaneously
    > registered with a number of providers and will ring if and when an
    > incoming call is offered by any of them.


    Yes, understand that.

    > I'm fumbling over the terms because I do not know how this capability of
    > being register, alert and available to accept incoming calls is named or
    > described by equipment vendors.


    I think your terminology isn't far off, and quite clear.

    Going back to the Asterisk box, that has no effective limit on the number
    of registrations. I have six on mine, and a block of DDIs that come in
    and are nicely separated. I also having incoming analogue on it, and that
    too is separated. I can call out on any of them. It's certainly worth
    considering.

    The weakest point probably isn't the Asterisk box, but your phone line.
    If that goes, you lose phone service. No different to a conventional
    line, really!

    (I don't actually have any IP phones, but I have an SPA2000 and an
    SPA8000 hooked into the house phone wiring).



    --
    Use the BIG mirror service in the UK:
    http://www.mirrorservice.org

    *lightning protection* - a w_tom conductor
    Bob Eager, Jul 4, 2011
    #15
  16. Anthony R. Gold wrote:

    > these, using one per incoming provider/phone number. But I am looking for a
    > device that can be simultaneously registered with a number of providers and
    > will ring if and when an incoming call is offered by any of them. Does the


    Most, if not all devices will do that. Your problem is not receiving
    calls from multiple clients, but rather registering with multiple clients.
    David Woolley, Jul 5, 2011
    #16
  17. On Tue, 05 Jul 2011 07:48:34 +0100, David Woolley
    <> wrote:

    > Anthony R. Gold wrote:
    >
    >> these, using one per incoming provider/phone number. But I am looking for a
    >> device that can be simultaneously registered with a number of providers and
    >> will ring if and when an incoming call is offered by any of them. Does the

    >
    > Most, if not all devices will do that. Your problem is not receiving
    > calls from multiple clients, but rather registering with multiple clients.


    Okay, I'm happy to accept the word client. Is there any available equipment
    that will allow multiple (say 4 to 6) clients to register with servers in
    order to be offered incoming calls? I believe my SPA3102 can register only
    one and I understood Graham to say that his PAP2 could register two.
    Anthony R. Gold, Jul 5, 2011
    #17
  18. Anthony R. Gold wrote:

    >Okay, I'm happy to accept the word client. Is there any available equipment
    >that will allow multiple (say 4 to 6) clients to register with servers in
    >order to be offered incoming calls? I believe my SPA3102 can register only
    >one and I understood Graham to say that his PAP2 could register two.


    This is _why_ I've been harping on about taking an open-source
    approach - I know, but please bear with me. If you buy a packaged
    solution, the people who made it were thinking about up-selling, so
    it'll be set up to be just barely capable of what the average consumer
    wants - and if you want something more complex, why, they'll sell you a
    more expensive box to do that. (Cisco in particular love to do this with
    their routers.)

    If - and I grant you it's not a universal condition - you are a
    minimally-competent Linux sysadmin, the only practical difference
    between having a Cisco/Linksys box (the modern ones run Linux
    internally, but you can't get at it) and a "proper" Linux machine with
    an FXO card in it is that the latter isn't subject to these
    marketing-based restrictions - you can do whatever you like with it.
    Roger Burton West, Jul 5, 2011
    #18
  19. On Tue, 5 Jul 2011 08:21:10 +0000 (UTC), Roger Burton West
    <> wrote:

    > Anthony R. Gold wrote:
    >
    >> Okay, I'm happy to accept the word client. Is there any available equipment
    >> that will allow multiple (say 4 to 6) clients to register with servers in
    >> order to be offered incoming calls? I believe my SPA3102 can register only
    >> one and I understood Graham to say that his PAP2 could register two.

    >
    > This is _why_ I've been harping on about taking an open-source
    > approach - I know, but please bear with me. If you buy a packaged
    > solution, the people who made it were thinking about up-selling, so
    > it'll be set up to be just barely capable of what the average consumer
    > wants - and if you want something more complex, why, they'll sell you a
    > more expensive box to do that. (Cisco in particular love to do this with
    > their routers.)
    >
    > If - and I grant you it's not a universal condition - you are a
    > minimally-competent Linux sysadmin, the only practical difference
    > between having a Cisco/Linksys box (the modern ones run Linux
    > internally, but you can't get at it) and a "proper" Linux machine with
    > an FXO card in it is that the latter isn't subject to these
    > marketing-based restrictions - you can do whatever you like with it.


    Far from being a minimally-competent Linux sysadmin, I am not even a totally
    incompetent Linux end user. I have plenty of Linux devices including routers,
    GPS sets, TV PVRs and satellite receivers and would be happy to consider
    buying an Asterisk appliance if one was available and could fulfil my needs.
    Anthony R. Gold, Jul 5, 2011
    #19
  20. On Tue, 5 Jul 2011 10:14:35 +0100, "Rob" <> wrote:

    > I use a DrayTek Vigor2820Vn (V=VoIP, n=wireless n) which handles/registers
    > upto 12 SIP accounts for both incoming and outgoing calls (although only 2
    > simultaneous SIP/VoIP calls can take place due to there being 2 physical
    > ports).


    Many thanks. I use both 2820 and 2920 (non-modem) routers in different
    locations for their dual WAN capabilities. Upgrading to VOIP versions may
    answer my needs if I can't find the capability in cheaper add-on equipment.
    Anthony R. Gold, Jul 5, 2011
    #20
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