Telecom Router Problems with emulated analog lines

Our main national telephone operator offers customers new services, such as Fiber, discarding the “old” ISDN studs. The important feature of this type of service lies in the fact that the two ISDN telephone channels are emulated by a router, but instead of being digital they are 2 single analog lines where a traditional analog telephone such as Sirio or a cordless telephone can be connected.

However, this type of service is suitable for residential use, where there is no switchboard and where the phones are connected directly to the telephone lines: the Telecom router, in fact, when a call arrives, makes the analog lines ring at the same time. This causes the switchboard to receive 2 calls at the same time, one of which should be cut down by the router as soon as the first is taken over, but this sometimes does not happen, with negative consequences on the operation of the switchboard.

In fact, when the two calls are routed to a ring group, the users of the latter will see two calls arrive: the first user who answers will speak regularly, but at the same time the second call, remaining still active, will make the other terminals ring, which answering they will not hear anything.

This phenomenon obviously also distorts the statistics on calls received by the switchboard.

If you are still in the decision-making phase for the transition to the new contract, you should indicate to the operator that there is a switchboard upstream of the router and that the two analog lines MUST NOT ring simultaneously when the same call arrives; this should be achieved by activating the automatic search on the router (which has a one-off cost of around € 30), which is no longer valid with the transformation from socket to router (remember in fact that in basic ISDN access this service is native).

If it is not possible for Telecom to solve the situation, it will be possible to try a trick to deceive the router, even if the problem of false statistics cannot be solved.


The procedure for solving problems with the Telecom router consists in configuring the input IVR: there must be a choice (input) and no event on failure must be configured.

This configuration forces the caller to type a choice to go ahead, while the phantom call, having no input, will stop in the IVR but will time out by knocking it down.

A similar IVR must also be present during the closing times. Should this procedure not work either, it will be necessary to change the type of router or operator: Telecom itself is installing Fritzbox 7590 router with ISDN interface.

The ISDN interface avoids in addition to the problem of the ghost call any problems in presenting the callerID (sometimes not detected) and also the problem of using the mobile phone as a terminal (UI setting: use mobile phone on group call) simultaneously with the fixed telephone from part of a user of a group: this causes the group to stop ringing as soon as the call arrives at the analog gateway.