Alternate Line Service

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The Alternate Line Service ( ALS ; . English about for Line change service ) is based on the CPHS specification, an extension of the GSM standards, a second phone number ready for outgoing and incoming calls. This can be selected via the mobile phone menu.

support

Most current devices from all manufacturers currently support this service. The SIM card informs the end device whether the network supports the Alternate Line Service via an entry in the Customer Service Profile (CSP). Android and iOS have not implemented this service.

In Germany, only E-Plus offers this service as a so-called PrivateLine . In this way, it is possible to separate private and business calls by means of bills divided into first and second line (first and second phone number).

In most end devices, separate acoustic signals and call diversions can be assigned to the two lines .

In Austria, ALS is offered by network operator A1 as Xtraline and by operator One / Orange as a number plan (previously One 2 Switch ). After the takeover of Orange by "three", ALS will be discontinued on November 30, 2014.

In Switzerland, the SIM cards of the Orange network operator are preconfigured for the ALS service, but this service cannot be activated here.

Non-standard-compliant implementation and problems with E-Plus SIM cards

According to the CPHS specifications, the ALS information is stored on the GSM SIM card in a specially reserved section, the CustomerServiceProfile (CSP). According to this specification, the value 0x80 should be stored in field 6F15 of the SIM card in service group code 0x06, which is then recognized and interpreted by the mobile phone so that the necessary menus for the second line are displayed. However, E-Plus SIM cards have the value 0x55 in this field, which is only interpreted as an ALS activation by Siemens mobile phones . Therefore, the use of the E-Plus Private Line is only possible with Siemens telephones. In addition, the ALS menus can be activated on some Nokia telephones using CSP override, some Motorola telephones display these menus anyway regardless of the SIM card, so the service can also be used here if necessary. Devices with UIQ 3.0 and newer Nokia phones recognize the E-Plus SIM cards correctly and therefore also support the service with E-Plus SIM cards. On some devices with Windows Mobile version 6.1 or higher, the menus can be activated using Julien Schapman's Advanced Configuration Tool software .

However, the use of the E-Plus-Privateline with ALS-capable telephones from other manufacturers is not possible due to the misconfiguration mentioned above.

Alternative implementation of the second number at Vodafone (D), O2 (D) and T-Mobile (D)

Vodafone , O2 and T-Mobile offer similar services in Germany with Duobill , Dual Line and Twinbill , however, the ALS standard is not used, but in principle two separate SIM card information is stored on a special SIM card , Switching between the lines is similar to the dual SIM adapters using the pin number or a SIM toolkit menu entry.

ALS vs. alternative implementation

Both solutions have both advantages and disadvantages:

The ALS solution is technically more elegant, a line selection for outgoing calls is possible without much effort via the context menu, and incoming calls can be signaled with different ring tones depending on the line. Disadvantages of this solution are that SMS or data transmission cannot be sent on the second line, and international roaming is not possible with the second line.

The solution used by T-Mobile and Vodafone is technically less elegant, only two SIM cards are stored on one card. To change the line at Vodafone, the mobile phone must be switched off and on again. The active number is selected when switching on by entering different PINs. T-Mobile has a mobile phone menu from which the number can be changed - with this provider you can also see which number is active on the mobile phone display. Mutual call diversions (also for SMS) are set up automatically. With Vodafone, on the other hand, in order to be reachable on both numbers at the same time, a call diversion must be set from the inactive line to the active line.

Signaling the line for incoming calls using different ring tones is therefore not possible with either provider.

The advantages are the practically unrestricted functions of the second line, since it is basically a second SIM card, SMS and data transmissions as well as international roaming are possible on the second line.

See also

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