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

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Big Question

Use E.164 or Not?

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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!)

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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

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E.164

• Cons out-weigh pros

• Various implementation options– Dial plan distribution– ENUM– DUNDi– Private ENUM or SIP redirect server

• Not discussed further here

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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

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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

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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.

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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?

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IVR Gateway

• Two-stage dialing through central GW• Gateway generates SIP.edu INVITE• dbaron@mit.edu = **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”?)

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Hash Registrar1/3

• Each campus forwards UA registrations to a central registrar

• Hash SIP.edu address to 8-10 digits

• dbaron@mit.edu = **338xxxxxxxxx

md5(‘dbaron@mit.edu’) % 109

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Hash Registrar2/3

• Hash collisions– Make ‘em rare– Resolve through an IVR (“Press one for

dbaron@mit.edu; two for alice@wonderland.edu.” )– 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.”)

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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

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Domain Redirect1/4

• Mnemonic campus prefixes

• Central redirect server interprets prefixes and redirects to campus proxy

• dbaron@mit.edu = **338648xxxxx• = **338xxxxx00648 “MIT”

Locally interpreted by MIT (could be extension or username hash)

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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)

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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)

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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…

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SIP.edu Reachability: Present and Future

NG Device Keypad

NG Device SIP.edu v1.0

Keypad

To:

From:

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SIP.edu Reachability: Present and Future

NG Device Keypad

NG Device UA Reg SIP.edu v1.0

Keypad UA Reg

To:

From:

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SIP.edu Reachability: Present and Future

NG Device Keypad

NG Device UA Reg SIP.edu v1.0

Keypad UA Reg, ISN ISN

To:

From: