Setup of ENUM-based services:The Generic Gateway Reference

Implementation

Michael HaberlerInternet Foundation Austria

11/2004

outline

• about us• problem & the basic techniques• call flows for voice + SMS • description of reference implementation• application example: virtual number resale

• lessons learned• survey of available components/suggestions for

trying things out

us & our role

• Internet Foundation Austria– Goal – fostering the Internet development in Austria– subsidiaries:

• nic.at GmbH – handling .at TLD – 400.000 domains, 35 people• enum.at GmbH – Tier1 registry for +43 e164.arpa until 2007• concluded operations contract for +43 with Austrian regulator in

8/2004– developed ENUM registry from scratch– startup of full service scheduled for Dec 9, 2004

• ipCom GmbH (in startup) – will provide:– Tier2 portal– ITSP supply services – PSTN/IP gateway, SMS/IM – goal is to develop the market by transferring R&D to services

• 5 people, 2+ years ENUM trial, platform development + operations experience

Internet & PSTN call legs

sip:anne@isp.at+43 780 1234

sip:bert@isp.de+43 780 5678

+43 1 5261670

+31 20 12345ENUMDNS

MediaGateway

The generic gateway trick

• The problem is getting services out of PSTN onto IP – other direction is usually easy. Use ENUM to figure out where the endpoint is.

• Igredients:– Take any service addressed by E.164 numbers. (voice, SMS,

IM, presence, Video..) for which you can provide a gateway.– Get a number range for IP endpoints.– Get relevant telcos to handover service to gateway (ISDN, SS7,

SMPP, 3G-324, whatever).– Create compatible IP endpoints with URI‘s, assign E.164

numbers & ENUM domains– ENUM lookup drives gateway, service delivery.

• Result: soft & user-configured gateway service.

Generic Gatway example:Voice

Telekom PSTN Switch

nic.at43.at

1. +43 780 123456

6.5.4.3.2.1.0.8.7.3.4.e164.arpa

4. sip:mah@nic.at43.at

sip:mah@nic.at43.at

5. INVITE sip:mah@nic.at43.at

PSTN-IP Gateway

2. +43 780.*

DNS

6. INVITE sip:mah@nic.at43.at

PSTN Internet

Generic Gateway example:SMS delivery

MO SMS Center

nic.at43.at

6.5.4.3.2.1.0.8.7.3.4.e164.arpa

4. sip:mah@nic.at43.at

sip:mah@nic.at43.at

5. MESSAGE sip:mah@nic.at43.at

at43 SMPPServer

2. SMS via SMPP

DNS

6. MESSAGE sip:mah@nic.at43.at

PSTN Internet

1. SMS an +43 780 123456

the enum.at generic gateway reference implementation (voice)

• covers PSTN->IP • does SIP, H.323 and ifax:mailto based on ENUM (public

or private)– functionality based on service set agreed in +43 intercarrier

working group

• uses ISDN PRI (now)• harmless investment – 2 Cisco AS5XX0s and 2 servers

will do - fully redundant• will scale, work and get service out• things it doesnt do:

– codecs Cisco doesnt like (yet)– easy handling of several number ranges– announcement text free of charge (TBD)

Generic Gateway Architecture

DNS

PSTN IP

RadiusAuthentication

Server

Perl CallRouting Script

RadiusAccounting

Server

Database

DNS Proxy

Procmail andifax PerlScript

SMTP Server

GenericGateway

Cisco GW

Single PC

Hardware/Software Cisco GW

• at least one PRA interface and one Fast Ethernet interface

• at least one voice feature card (vfc) module installed (DSPs for VoIP).

• Cisco IOS version– IOS (tm) 5300 Software (C5300-JS-M), Version

12.2(13)T3, RELEASE SOFTWARE (fc2)

• Fax onramp application– fax_on_vfc_onramp_ap

Hardware/Software Helper PC

• Standard x86 compatible server hardware• Operating system: Debian woody 3.0r2 Linux• Radiator (or any other radius server which supports

execution of perl scripts and database accounting)• Perl (included in Debian distribution)• Perl enum.pm module from

http://jprs.co.jp/enum/software/ENUM.pm• postgresql database (for storing accounting data,

included in Debian)• exim SMTP server (for delivery of fax emails, included in

Debian)• procmail (for email handling, included in Debian)• dnsproxy from http://www.wolfermann.org/dnsproxy.html

with modifications to rewrite “old-style” NAPTRs.• tftpd server (included in Debian)

application example:virtual number wholesale

• virtual presence in a location is an issue (not just for offshore tax-shelters ;)

• there‘s a wholesale market starting• basically number -> SIP URI mapping• around 1$/month wholesale• straightforward to implement with

number range, generic gateway andENUM registrar

virtual number resale: +43 case

generic gatewayoperated by

telco+43 780ENUM-drivennumber range

ENUMregistrar

operatingcontract

ENUM

subscriber

ITSPoffering

virtual numbers

subscription +VoIP service

wholesalecontract

provisioningprotocol

delegation

lookup

virtual number resale: benefits

• telco: one gateway, any service, any business case

• registrar: potentially popular service, especially in countries with large expatriate communities

• user: can use number on-net too besides being reachable from PSTN

• this is what is under construction in Austria (available Q1/2005)

what we would do different if we were grown up

• have an SS7/ISUP translator driving the MG with SIGTRAN

• look into VoIP/GSM roaming (see BridgePort MVNO/SIP gateway)

• to do list:– SMS/sms:sip/sms:mailto gateway (just about ready)– generalized enum rewriting (so much about standards

compliant hardware)– generalized stack activation

this is an open source product

• watch www.enum.at or drop me an email

what we are investigating/playing with

• we‘re building a generic gateway for SMS for at43 and then +43 780

• sms:sip - map onto SIP MESSAGE, fallback to sms:mailto

• mobile operators converge on the „Wireless Village“ IM & presence protocol. This is an URI, and thus an ENUM opportunity. Look at www.webmessenger.com.

• an ENUMservice for Jabber (IDA)• The way Push-to-Talk is implemented is asking

for Internet extension.• we‘re looking into a UMTS Video-> SIP H.263

gateway service with ENUM mapping.

recommended links for hands-on experience• Basic SIP-based VoIP, Instant Messenging, Presence:

– get an account at www.fwdnet.org– try the Windows Eyebeam SIP client – www.xten.com– try instant messenging with SIP and the Windows Messenger

• note this is not the same as Microsoft Messenger!

– Linux: try Linux kphone http://www.wirlab.net/kphone/– good information source on VoIP: http://www.voip-info.org

• Ready for your own SIP server?– try SIP Express Router – www.iptel.org– try the Asterisk IP PBX – www.asterisk.org– both are ENUM enabled out-of-the-box

• try the ENUM resolver at http://jprs.co.jp/enum/software/software.html

• to read up on ENUM, try http://enum.nic.at