1-5-7-1

1-5-7-1 is the name of a family of calling features in the United Kingdom, for residential and business telephone lines and for mobile telephones, that are provided by BT Group and several other telephone service providers. The family is named after the telephone number 1571, the special service number that is used to access it. Call Minder is the name of BT's highest level of 1571 service.

Land lines

The 1571 feature was introduced by BT Group to the UK after planned in the 1990s after they digitalized all the telephone exchanges. As of 2006 several other telephone service providers in the United Kingdom also provided 1571 answering services, including One.Tel, Platinum Telecom, Kingston Communications, and Manx Telecom. Most such providers rely on a local loop that is owned by BT Group. However, it is also available from providers that have their own local loops, such as Virgin Media.

In 2001 BT Group launched its Answer 1571 service as a free service, available at no extra cost to its existing telephone line customers. In 2007 a charge of £1 was introduced for any month in which two chargeable calls are not made on the line (this might apply, for instance, to people who have Carrier preselect with another telephone company). The Answer 1571 service, a cut-down version of BT Group's Call Minder service, allows a calling party to leave messages when the called party is engaged or does not answer within a fixed number of rings. The system allows for the storage of up to 10 such messages, each of which can be up to 2 minutes long, for up to 20 days. To indicate to called parties that they have waiting messages, the exchange sends an interrupted dialling tone to them when they take their telephone off-hook. The called party can retrieve the messages by dialling the number 1571.

The feature of Answer 1571 that cannot be implemented on an answering machine is that the machine cannot record messages when the called party is engaged on another call. This was seen to be a considerable advantage over an answering machine to those who had dial-up access to Internet, because dial-up connections can often involve long periods when the line is engaged.

Disadvantages of Answer 1571:

• it can cause problems for computer telephone line modems, which are unable to recognize the interrupted dialling tone as a dialling tone and which will thus refuse to make outgoing calls, reporting being unable to detect a dialling tone;
• it costs the calling party the minimum connection charge to discover that the called party is engaged, even if they do not wish to leave a message, whereas obtaining the engaged tone incurs no connection charge. The Gosport & Fareham branch of the Multiple Sclerosis Society, as well as several others, recommends as a tip for saving money when making telephone calls to "count six rings and hang up before the expensive voice starts charging you";
• many answering machines implement call screening, which 1571 cannot do: the answering machine picks up the call with its speaker active, so that the user, if available, can listen to what the caller says, and pick up the phone only if they want to speak with the caller;
• some machines can record conversations, which 1571 of course cannot do.

On top of the free or paid Answer 1571 services, BT provides an additional services at an extra charge: the 1571 Text Alerts service sends a text message to a designated mobile telephone number whenever a calling party leaves a new message. Another service was withdrawn in March 2009: 1571 Online allowed customers to retrieve their stored messages via the World Wide Web.

A problem with the 1571 Text Alerts system that existed and BT's website failed to point out as of 7 June 2007 is that if a mobile phone number is transferred from another provider to either Virgin or T-mobile, the alert system will not work; phone messages will be stored, but text message alerts will not be sent.

As of December 2011 BT offers two services accessed via the 1571 number. None of the services can be disabled or re-enabled by the user, but must be ordered or cancelled, with a lag of several days.

• Answer 1571, free. Calls answered after 7 rings. Up to 10 call stored for up to 20 days. Fixed greeting message. Messages not accessible remotely by ringing in.
• Call minder, £3.15/month (subject to change), as above but 30 messages, stored for 30 days, can answer after 0, 4, 7, or 10 rings (nominal, may vary), can store numbers of callers who leave no message, messages can be accessed by dialling in with an identification number, can record personal greeting.

The number of rings before answering is not guaranteed, and may be longer or shorter than the specified number. This can be a problem if a 1571 service is used in conjunction with an answering machine; for example, an answering machine which supports remote access by ringing in can be switched on when a user of the free or cheaper 1571 service that does not allow remote access is away for several days and needs to check messages while away. It is necessary to ensure that the machine answers before the shortest possible number of rings, otherwise 1571 will pick up calls instead. For example the BT Response 75 machine has a mode which answers after 2 rings if there are new messages, and 6 rings if none, allowing the user to call in to check for messages and hang up after say 4 rings if no messages, saving the cost of the call; this is negated if Answer 1571 may answer calls before the machine picks up (nominally after 7 rings), recording messages that the user cannot access.

Mobile telephones

To its mobile telephone business customers BT Group provides a 1571 Voicemail service, which is similar to the service provided to landlines. Calling parties can leave messages when the mobile telephone is switched off, when it is in an area of reduced coverage, when it is on another call, or when the call is not answered within a fixed number of rings.

Further reading

• "BT 1571". BT products and services. Retrieved 2006-12-19.