isdnBearerPeerAddress 1.3.6.1.2.1.10.20.1.2.1.1.4

The ISDN address the current or last call is or was connected to. In some cases, the format of this information can not be predicted, since it largely depends on the type of switch or PBX the device is connected to. Therefore, the detailed format of this information is not specified and is implementation dependent. If possible, the agent should supply this information using the E.164 format. In this case, the number must start with '+'. Otherwise, IA5 number digits must be used. If the peer ISDN address is not available, this object has a length of zero.