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  • X.25 access Janet TACS converter. This telnet address is an X.25 to TCP/IP gateway. Sometimes accessing online databases or database hosts from UK university or academic research libraries via TCP/IP i.e. the Internet (web or telnet) can be slow and congested during peak hours. Another route is available involves telnetting to the Janet TACS (Terminal Access Conversion) service. In order to use this route you need to have a TACS account via JANET Customer Service service@ukerna.ac.uk.

  • X.25/frame relay Public Data Networks, (PDNs) websites.
  • Access to remote databases online (especially via remote database hosts), are usually via several different global computer data communication protocols and networks, i.e. Wide Areas Networks or WANs. In Europe, some widely used switched WAN services are based on: a) public X.25, European EuropaNet networks, such as the (IXI International X.25 Interconnect), e.g. EARN nodes such as JANET in the UK, DFN in Germany, GARR in Italy and SWITCH in Switzerland, b) TCP/IP, c) ISDN, d) frame relay, e) ATM and f) SMDS. Numerous private (WAN) data networks such as DIALOG's DIALNET also exists as an alternative.

    X.25 PDNs were for many years, (before the availability of web or telnet access to databases and databanks via TCP/IP), the most popular packet switched public WANs used for accessing databases. Using such networks, one can access very remote databases overseas, for the cost-effective price of a local modem call (e.g. via a Point of Presence or POP, i.e. public-dial node), instead of calling the remote database server directly, via a costly international modem call. E.g. librarians in the US can access BLAISE-LINE in the UK via a local modem number using the American Sprintnet (Telenet) service, likewise UK medical information scientists can access DIALOG and NLM databases in the US using British Telecom's GNS Dialplus service.

    Since national/government telecommunications (PTT) monopolies like British Telecom, were the first to offer packet switching data services, most major PDNs worldwide as such are owned by them, although following deregulations in the telecommunications industry, some telecom operators such as British Telecom have been privatised and the telecommunications market open to foreign competitors. Using PDNs such as X.25 services, is quite simple, once you have a "Network User Identification" (NUI) from the PDN carrier, and also the Network User Address (NUA) of the hosts you want to access. X.25 database access may be via dial-up access (cheaper, but temporary), or dedicated access (expensive but permanent). Most PDNs end with "pac" which means Packet Switching!

    Starting from about middle 1991, X.25 PDNs has been overshadowed (and in many developed nations almost replaced) by the more advanced and faster frame relay PDN and ATM (a.k.a. cell relay), alongside the popular TCP/IP. But X.25 database access remains popular in developing nations.

    The following are the official websites of some major X.25/frame relay PDNs services. Telecom operators or PDN operators are in brackets, when you access thier web site, look under products and services etc, then under data or data communications etc. For more telecom operators, see world telecom operating companies.

  • Arpac: (Telecom Argentina) Argentina.
  • Austpac/Data Access: (Telstra) Australia.
  • Radausdata: Datex-P: (Post and Telekom, Radio-Austria) Austria.
  • DCS: (Belgacom) Belgium.
  • Interdata/Renpac: (Embratel) Brazil.
  • Bulpac: (Bulgarian Telecommunications Company, BTC) Bulgaria.
  • Chinapac: (China Telecom) China.
  • Datapac: (Stentor) Canada.
  • Coldapac: (Telecom Colombia) Colombia.
  • Transpac: (France Telecom) France.
  • Datex-P (Deutches Telekom) Germany.
  • Hellaspak: (OTE) Greece.
  • Datanet: (PTT Nederland/KPN) Holland.
  • IDAS: (Hong Kong Telecom) Hong Kong.
  • Gateway Packet Switching Network,GPSS: (Videsh Sanchar Nigam) India.
  • SKDP: (Satelindo) Indonesia.
  • Eirpac/Postnet: (Telecom Eireann) Ireland.
  • Isranet: (Bezeq) Israel.
  • Itapac: (Telecom Italia) Italy.
  • Venus-P/DDX-P/NIS-NET: (Nippon Telegraph and Telephone NTT) Japan.
  • Maypac: (Telekom Malaysia) Malaysia.
  • Iusanet: (Telmex) Mexico.
  • Pacnet: (Telecom New Zealand) New Zealand.
  • Polpak: (Telekomunikacia Polska) Poland.
  • SADB: (Portugal Telecom) Portugal.
  • Perunet: (Telefonica Peru) Peru.
  • Rompac: (Romtelecom) Romania.
  • Isanet/Infotel: (PTT Russia) Russia.
  • Iberpac: (Telefonica Espana) Spain.
  • Telepac: (Swisscom) Switzerland.
  • Datapak: (Telia) Sweden.
  • Dacom-Net: (Korea Telecom) South Korea.
  • Saponet: (Telecom South Africa) South Africa.
  • Global Network Services, GNS/PSS: (British Telecom, BT) and Mercury 5000: (Cable & Wireless) UK.
  • Urupac (Antel) Uruguay.

    U.S. (numerous due to open liberal telecommunications market with many major players).

  • Sprintnet/Telenet (Sprint/GTE) Has very good resources on frame relay.
  • Tymnet (MCI)
  • Istel Infotrac (At & T)
  • Accunet (At & T)
  • Easylink (At & T)
  • Worldnet (At & T)
  • Pulsenet (Bell)
  • Autonet
  • Digipac (US West)
  • MarketNet
  • Impacs (MCI)
  • Pulselink (Bell)
  • Infonet
  • Wangpac (Bell)
  • TRT
  • PSN (Ameritech)
  • Infopath (Nynex)
  • GraphNet

    If accessing databases or database hosts with a laptop computer and mobile phone, a list of GSM mobile phone networks offering X.25 access is at the W directory, under "World GSM mobile phone network directory"


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