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SIP.edu call 6/23/05 “SIP.edu by Numbers” 1
SIP.edu by Numbers
Ben TeitelbaumSIP.edu Working Group Call
June 23rd, 2005
SIP.edu call 6/23/05 “SIP.edu by Numbers” 2
PSTN
Big Problem
How to SIP from a 12-key phone?
IP Desk Phones
Cell Phones
Legacy DeskPhones
SIP.edu call 6/23/05 “SIP.edu by Numbers” 3
Big Question
Use E.164 or Not?
SIP.edu call 6/23/05 “SIP.edu by Numbers” 4
Use E.164 Numbers
• Pros– Seamless
interoperability with PSTN
– No need to change numbers
• Cons– Not our numbers– Finite resource– Regulatory implications “If
it walks like a duck…”– Seamless interoperability
with PSTN (i.e. users should notice that something has changed!)
SIP.edu call 6/23/05 “SIP.edu by Numbers” 5
Use Non-E.164 Numbers
• Pros– Our numbers– Numbers could be
more mnemonic– Users will notice that
something has changed
– Lighter regulatory touch (maybe)
– Could fit into E.164 down the road (+87810…)
• Cons– Calling from PSTN
would require two-stage dialing
– Calling from a legacy campus environment would require an escape code
SIP.edu call 6/23/05 “SIP.edu by Numbers” 6
E.164
• Cons out-weigh pros
• Various implementation options– Dial plan distribution– ENUM– DUNDi– Private ENUM or SIP redirect server
• Not discussed further here
SIP.edu call 6/23/05 “SIP.edu by Numbers” 7
Non-E.1641/2
• Pros out-weigh cons• Some design considerations
– Numbers derived from SIP.edu addresses, derived from existing extensions, or completely new?
– Address structure• Flat or hierarchical?• Fixed length or variable-length?
– Escape codes
SIP.edu call 6/23/05 “SIP.edu by Numbers” 8
Non-E.1642/2
• Various implementation options– IVR Gateway– Hash Registrar– Domain Redirect– Others?
• Let’s discuss them…– First, though, a few words on…
• Address Structure• Escape Codes
SIP.edu call 6/23/05 “SIP.edu by Numbers” 9
Address Structure*
• (prefix)(hash)– Requires central authority to resolve hash
• (prefix)(user)(domain)– Like email– Perhaps “00” could be used as separator
• (prefix)(domain)(user)– Maps to DNS (e.g. non-E.164 ENUM)– (user) part could be interpreted locally
* Thanks to Ed Guy for this taxonomy.
SIP.edu call 6/23/05 “SIP.edu by Numbers” 10
Escape Codes
• Campus dialing plans must designate some escape code to indicate that a “SIP.edu number” follows– E.g. **EDU (**338)– Local conventions will vary
• Will variable-length numbers be a problem?
SIP.edu call 6/23/05 “SIP.edu by Numbers” 11
IVR Gateway
• Two-stage dialing through central GW• Gateway generates SIP.edu INVITE• [email protected] = **338 then…
– Speak “dbaron at MIT dot e-d-u” (voice recognition)
– Type 3122217363620614381 (two-tap DTMF codes)
– T9® predictive text—probably not(proprietary technology; dictionary too big)
• Voice only (“I-IM-R”?)
SIP.edu call 6/23/05 “SIP.edu by Numbers” 12
Hash Registrar1/3
• Each campus forwards UA registrations to a central registrar
• Hash SIP.edu address to 8-10 digits
• [email protected] = **338xxxxxxxxx
md5(‘[email protected]’) % 109
SIP.edu call 6/23/05 “SIP.edu by Numbers” 13
Hash Registrar2/3
• Hash collisions– Make ‘em rare– Resolve through an IVR (“Press one for
[email protected]; two for [email protected].” )– Or (maybe) don’t resolve (“Bad luck, you will have
to get a new email address if you want to be SIP-able by numbers.”)
SIP.edu call 6/23/05 “SIP.edu by Numbers” 14
Hash Registrar3/3
• Pros– Knowing an email
address knowing the number
– Simplifies identity management
• Users don’t get explicit numbers
– CGI “white page” can compute hash and produce number
• Cons– Only registered UAs
reachable by number– Collisions– Requires campus proxy
/ registrar to pass REGISTERs
SIP.edu call 6/23/05 “SIP.edu by Numbers” 15
Domain Redirect1/4
• Mnemonic campus prefixes
• Central redirect server interprets prefixes and redirects to campus proxy
• [email protected] = **338648xxxxx• = **338xxxxx00648 “MIT”
Locally interpreted by MIT (could be extension or username hash)
SIP.edu call 6/23/05 “SIP.edu by Numbers” 16
Domain Redirect2/4
Default Campus Prefixes252269 (albany) 36679 (emory) 63 (nd) 8268 (tamu) 84692 (uiowa) 883927 (utexas)2749662 (arizona) 3268 (famu) 648 (niu) 828 (tcu) 8482 (uiuc) 8865336 (utoledo)278283 (astate) 328 (fau) 6548 (njit) 836753 (temple) 85267 (ukans) 88768849378376 (utsouthwestern)278 (asu) 348 (fiu) 6678 (nmsu) 836637733 (tennessee) 859 (uky) 888572 (utulsa)282876 (auburn) 378 (fsu) 66325 (nodak) 839278324 (texastech) 862463 (umaine) 886 (uvm)229567 (baylor) 428324 (gatech) 667843278376 (northeastern) 862 (tmc) 862795263 (umaryland) 896 (uwm)22 (bc) 4367438696 (georgetown) 667849378376 (northwestern) 88387 (tufts) 86277 (umass) 8996 (uwyo)23753539 (berkeley) 468 (gmu) 698 (nyu) 885263 (tulane) 8622 (umbc) 8263372458 (vanderbilt)2478 (bgsu) 478 (gsu) 638 (odu) 82 (ua) 863 (umd) 828 (vcu)2464426866 (binghamton) 498 (gwu) 64468 (ohiou) 822 (uab) 86365 (umdnj) 84744642 (virginia)2723539 (bradley) 4278273 (harvard) 6478 (ohsu) 823 (uaf) 86424 (umich) 88 (vt)27263347 (brandeis) 429244 (hawaii) 6578283 (okstate) 824 (uah) 8652 (umkc) 9274464866 (washington)27696 (brown) 4278283 (iastate) 6536477 (olemiss) 825766 (uakron) 866 (umn) 92963 (wayne)28 (bu) 4634262 (indiana) 6778 (orst) 8257 (ualr) 867 (umr) 938 (wfu)2833256 (buffalo) 468376382 (internet2) 678 (osu) 8267 (uams) 8675 (umsl) 9424482 (wichita)298 (byu) 478 (isu) 68 (ou) 8275 (uark) 868 (umt) 9433637 (widener)2257659 (calpoly) 548 (jhu) 739 (pdx) 82 (uc) 862 (unc) 9472 (wisc)22578283 (calstate) 57867 (jsums) 7488 (pitt) 8232847 (ucdavis) 864 (unh) 96 (wm)2258324 (caltech) 5368 (kent) 774623866 (princeton) 823472 (ucdhsc) 865 (unl) 96424 (wmich)252736668 (claremont) 578 (ksu) 778 (psu) 823 (ucf) 8658 (unlv) 974 (wpi)2536766 (clemson) 534444 (lehigh) 787383 (purdue) 82442246 (uchicago) 866 (unm) 974448 (wright)258 (clu) 5684784553 (louisville) 7423 (rice) 824 (uci) 867 (unr) 978 (wsu)268 (cmu) 578 (lsu) 748 (rit) 8252 (ucla) 868 (unt) 98785 (wustl)26567236 (colorado) 582 (luc) 762437837 (rochester) 82666 (uconn) 8673466 (uoregon) 988 (wvu)265678283 (colostate) 627783883 (marquette) 774 (rpi) 8267 (ucop) 87366 (upenn) 9253 (yale)26586242 (columbia) 6296 (mayo) 7884377 (rutgers) 827 (ucr) 877 (upr)2676355 (cornell) 6367447 (memphis) 72 (sc) 8272 (ucsb) 874 (uri)2784299273 (csuhayward) 64264 (miami) 7378283 (sdstate) 8272 (ucsc) 872 (usc)2786446 (csuohio) 64776874 (missouri) 73278 (sfasu) 8273 (ucsd) 873 (usd)282 (cua) 648 (mit) 748 (shu) 8273 (ucsf) 873 (usf)2978 (cwru) 6668262 (montana) 748 (siu) 8335 (udel) 876 (usm)327866884 (dartmouth) 6778283 (msstate) 758 (slu) 835 (ufl) 878 (usu)337285 (depaul) 678 (msu) 768 (smu) 842 (uga) 882 (uta)373935 (drexel) 688 (mtu) 78263673 (stanford) 84 (uh) 8824 (utah)3853 (duke) 6872 (musc) 786972 (sunysb) 842 (uic) 88325527 (utdallas)328 (ecu) 6278 (ncsu) 797 (syr) 843246 (uidaho) 8837 (utep)
SIP.edu call 6/23/05 “SIP.edu by Numbers” 17
Domain Redirect3/4
• Some defaults collide– mit = niu = 648
• Others have colliding prefixes– 28 (bu)– 282 (cua)– 282875 (auburn)
• Suggested policy– First come, first served– Can’t have a default unless
its yours– Resolve conflicts
• Different lengths– mit + 5-digits– niu + 6-digits
• Numbering knowledge– mit + [2357][0-9]{4}– niu + [468][0-9]{4}
• Use a non-default prefix– 645 (nil)
SIP.edu call 6/23/05 “SIP.edu by Numbers” 18
Domain Redirect4/4
• Pros– Each campus can
number its own way• Existing extensions• Username hash• New numbers
– Reaches all campus phones
– Prefix gold rush
• Cons– Prefix gold rush– Prefix collision
resolution could get tricky
I like this option!
Full Disclosure…
SIP.edu call 6/23/05 “SIP.edu by Numbers” 19
SIP.edu Reachability: Present and Future
NG Device Keypad
NG Device SIP.edu v1.0
Keypad
To:
From:
SIP.edu call 6/23/05 “SIP.edu by Numbers” 20
SIP.edu Reachability: Present and Future
NG Device Keypad
NG Device UA Reg SIP.edu v1.0
Keypad UA Reg
To:
From:
SIP.edu call 6/23/05 “SIP.edu by Numbers” 21
SIP.edu Reachability: Present and Future
NG Device Keypad
NG Device UA Reg SIP.edu v1.0
Keypad UA Reg, ISN ISN
To:
From: