[SIPForum-discussion] Question Regarding "One Number, Multiple Phones"

Gopalakrishnan N saigop at gmail.com
Wed Aug 12 04:56:40 UTC 2015

The reason for this "BUT, here is the problem.  Once one of them answers
the call, all others are blocked from joining the conversation. " it might
be the half duplex of your analog phones connected to the softswitch.

Probably you can use a SIP server, and connect some IP phones or softphone,
which your issue can be addressed, and as you asked, you can have different
extensions for each phone and incoming call will ring for all phones, if
any one is answered others extensions will be free, and it can be used.

Probably you can use Asterisk, in place of this.

Hope I have answered.


On Mon, 10 Aug 2015 at 18:22 SMITH, BILLY R GS-11 USAF AETC 81 TRSS/TSUS <
billy.smith.5 at us.af.mil> wrote:

> Hello,
> I have a question regarding "One Number, Multiple Phones".  In a standard
> PSTN household, a family may have many phones in different rooms.  When
> there is an incoming call, all phones ring and any one can answer it.  Most
> importantly, at any time, any one of the other phones can pick up on the
> call.  Is this possible using SIP?  I have read the RFC, but being a VoIP
> novice, I am unable to see where this is addressed.  From what I
> understand, some vendors (i.e. BroadSoft) have addressed this need in a
> proprietary manner, but it has not been addressed as a general feature of
> SIP.
> This is not simply an academic issue for me.  We are in the process of
> replacing a meridian mini switch with a VoIP softswitch.  This is for a
> classroom configuration where students are in a simulated "Control Center"
> and they interact with the Instructor who acts as numerous outside
> agencies.  There is no connectivity outside the classroom.  In the real
> world Control Centers we are simulating, there is the ability to have the
> same number on a multi-line phone at various working positions.  At any
> time, students working in these positions need to be able to answer and/or
> join in to an existing call.
> I understand there are ways within SIP to set up "conferences" that allow
> you join conversations using a dial-in/password sort of thing, but I need
> it to act just like an ordinary PSTN phone.
> The current VoIP soft switch we are using provides most of the
> functionality I am looking for.  It allows up to three phones to register
> with the same number.  Incoming calls ring on all three handsets and any of
> them can answer the call.  BUT, here is the problem.  Once one of them
> answers the call, all others are blocked from joining the conversation.  Do
> you know of any way for me to accomplish this?
> I appreciate any light you can shed on this topic,
> Billy Smith
>         //SIGNED//
>         Billy R. Smith, CIV, DAF
>         Programmer Analyst, 81 TRSS/TSUS
>         DSN: 591-8448  Comm: (228) 376-8448
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