Re: [Linphone-developers] SIP address or phone number:

[Petr Pisar]

On Mon, Aug 17, 2009 at 11:28:23AM -0500, Nathan Stratton wrote:
> On Mon, 17 Aug 2009, Petr Pisar wrote:
>
>> On Sun, Aug 16, 2009 at 05:58:16PM -0500, Nathan Stratton wrote:
>>>
>>> The box says "SIP address or phone number:" but only sip URIs work, 
>>> should
>>> I also be able to enter a phone number such as just "18323303810"?
>>>
>> In former Linphone version there was possibility to input
>> "sip:18323303810".  It used "host" utility (thus unix only feature) to
>> query ENUM records. If sip address was found, Linphone INVITEd such
>> address.
>>
>> However I think contemporary version does not support it (check it) and
>> such address is still ill because RFC3976 reserves "tel:" URI for this
>> purpose.
>>
>> OTOH commercial carrier solutions (like some big softswitches made by
>> Siemens) usually misuse the sip: URI to carry telephone numbers in way
>> "sip:address@hidden".
>
> Why not have linphone accept anything entered without sip: and insert sip:
> before and @proxy after?
>
I'm strongly against this approach as I described above. From point of theory
and URI handling, <sip:address@hidden> is not equaled to <tel:N> in general. 
Anybody
is free to register <sip:address@hidden> on his registrar. Thus embeding 
telephone
number into sip: URI is specific to local SIP routing policy and no obligation
in this direction should bee assumed. Also public phone numbers (E.164) are
(usually) maintained by authorites different from local SIP operator,
therefore overloading sip: namespace is wrong way if one recalls SIP is not
about numbers only.

Be ware that SIP protocol allows to INVITE any URI including tel: URI.

Thus if you don't want ENUM resolver in caller end-point, you can delegate
this functionality to your (or parental, possibly rescursively) proxy. Any
not-ENUM aware SIP device should pass the tel: request to upstream (if
defined) or return Not Found error message. This brings contra-question to
your question: What if linphone has no proxy? Which domain would be appended?
None? This would be invalid sip: URI. The tel: URI is the right solution.

-- Petr

pgp5ptLxky7yf.pgp
Description: PGP signature