asterisk users - Nov 2019 - multiple softphone clients and same/different account credentials

(I'm new to Asterisk, after having started VOIP with vat on the mbone in
the 90s.)

I am setting up my first Asterisk system, and trying to read
docs/guidance and follow best practices.  I have read the 5th Edition of
"Asterisk: The Definitive Guide" and like the 3rd Edition on the web
it
recommends that hardphones and softphones both have a unique name
distinct from any concept of extension.

 
http://asteriskdocs.org/en/3rd_Edition/asterisk-book-html-chunk/DeviceConfig_id283201.html

Then the 5th edition goes on to give an example with a hardphone and a
softphone associated with one individual, where the hardphone is named
by MAC address and the softphone by JIM_VANM_SOFT (p. 61).

Despite talking about separating extensions, phone names, and people, it
seems clear that a softphone is usually personal to a person (unless
it's a desk phone via a computer, but I'm talking about the personal
type).

THe book does not address the notion that a user might be given
credentials and then configure them on a number of softphone-type
devices simultaneously, e.g. a smartphone, a tablet, and two laptops.
When getting service from an ITSP, it seems there are credentials and
they don't want to know the details of how many softphones you are
using.

So which option is preferred?

  A) Have a softphone aor/auth_user/password for a particular human, and
  expect them to configure it on multiple devices.  Do not worry that 1)
  multiple are registered at once (because that's normal in SIP) and 2)
  asterisk has no idea which is which (because the intent is to place a
  call to that person)

  B) issue credentials per device and keep them all separate.  Use
  extensions.conf to ring them all

Having written the question out carefully, it seems obvious that A is
the way to do this, but it's sort of contrary to the advice in the book
so I thought I would ask.

Thanks,
Greg

I'm no expert on the user side of things, but I would prefer option A. Of
course, this is completely your preference. Asterisk will allow either
option, so you have some flexibility there. One of the advantages of option
A is that you can have multiple devices (like you mentioned) that can all
be rung at once simply if the user has a desk phone, mobile work phone, etc.

On Mon, Nov 25, 2019 at 6:44 PM Greg Troxel <gdt at lexort.com> wrote:
> (I'm new to Asterisk, after having started VOIP with vat on the mbone
in
> the 90s.)
>
> I am setting up my first Asterisk system, and trying to read
> docs/guidance and follow best practices.  I have read the 5th Edition of
> "Asterisk: The Definitive Guide" and like the 3rd Edition on the
web it
> recommends that hardphones and softphones both have a unique name
> distinct from any concept of extension.
>
>
>
http://asteriskdocs.org/en/3rd_Edition/asterisk-book-html-chunk/DeviceConfig_id283201.html
>
> Then the 5th edition goes on to give an example with a hardphone and a
> softphone associated with one individual, where the hardphone is named
> by MAC address and the softphone by JIM_VANM_SOFT (p. 61).
>
> Despite talking about separating extensions, phone names, and people, it
> seems clear that a softphone is usually personal to a person (unless
> it's a desk phone via a computer, but I'm talking about the
personal
> type).
>
> THe book does not address the notion that a user might be given
> credentials and then configure them on a number of softphone-type
> devices simultaneously, e.g. a smartphone, a tablet, and two laptops.
> When getting service from an ITSP, it seems there are credentials and
> they don't want to know the details of how many softphones you are
> using.
>
> So which option is preferred?
>
>   A) Have a softphone aor/auth_user/password for a particular human, and
>   expect them to configure it on multiple devices.  Do not worry that 1)
>   multiple are registered at once (because that's normal in SIP) and 2)
>   asterisk has no idea which is which (because the intent is to place a
>   call to that person)
>
>   B) issue credentials per device and keep them all separate.  Use
>   extensions.conf to ring them all
>
> Having written the question out carefully, it seems obvious that A is
> the way to do this, but it's sort of contrary to the advice in the book
> so I thought I would ask.
>
> Thanks,
> Greg
>
> --
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-- 
Benjamin Ford
Software Engineer
256-428-6147
Check us out at www.sangoma.com
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>> So which option is preferred?
>>
>>   A) Have a softphone aor/auth_user/password for a particular human,
and
>>   expect them to configure it on multiple devices.  Do not worry that
1)
>>   multiple are registered at once (because that's normal in SIP)
and 2)
>>   asterisk has no idea which is which (because the intent is to place a
>>   call to that person)
>>
>>   B) issue credentials per device and keep them all separate.  Use
>>   extensions.conf to ring them all
>>
>> Having written the question out carefully, it seems obvious that A is
>> the way to do this, but it's sort of contrary to the advice in the
book
>> so I thought I would ask.
Ben Ford <bford at digium.com> writes:
> I'm no expert on the user side of things, but I would prefer option A.
Of
> course, this is completely your preference. Asterisk will allow either
> option, so you have some flexibility there. One of the advantages of option
> A is that you can have multiple devices (like you mentioned) that can all
> be rung at once simply if the user has a desk phone, mobile work phone,
etc.
Thanks.  It seems that A allows the user to choose devices without
changing the PBX config, and that the real issue is if one wishes to
allow calling the various devices separately, or if they are really just
one logical device.   In this case I intend them to  be one logical
device as in "dial the set of softphones Alice has configured and
currently has connected".

I have looked further and turned up two wrinkles, one of which is easy
and obvious in hindsight:

  one has to set max_contacts high for the user's softphone aor:
   
https://blogs.asterisk.org/2017/11/29/pjsip-mis-configuration-can-cause-loss-sip-registrations/

and the second appears to be an artifact of syntax processing and not
trivial to deal with.

  PJSIP doesn't dial all contacts when dialing an aor, so one needs to
  use PJSIP_DIAL_CONTACTS.  However, that can return the empty string
  and thus lead to a syntax error, leading to the need to write code to
  fix formatting:
   
https://asteriskfaqs.org/2019/06/09/asterisk-users/dialpjsip_dial_contactsalice-pjsip_dial_contactsbob-how-not-to-fail-if-one-endpoint-has-no-registered-aor.html

For the second issue, it would be nice if Dial just discarded empty
destinations, as in

  Dial(PJSIP/foo&)
  Dial(PJSIP/foo&&PJSIP/baz)

as would result from the following if there were no bar registrations

  Dial(PJSIP/foo&${PJSIP_DIAL_CONTACTS/bar})
  Dial(PJSIP/foo&${PJSIP_DIAL_CONTACTS/bar}&PJSIP/baz)

which seems to be how almost everyone (perhaps actually everyone) wants
to use PJSIP_DIAL_CONTACTS.


It is starting to seem that configuring multiple endpoints is easier
than maintaining code to remove a trailing or double &.

Greg