A European format for digital transmission. E1 supports signals at 2 Mbps (32 channels at 64Kbps, with 2 channels reserved for signaling and controlling), versus the T1, which carries signals at 1.544 Mbps (24 channels at 64Kbps).
Using Voice over Internet Protocol (VoIP) calling applications on your mobile phone can save you money if you make a lot of international calls or travel out of the country often. iPhone users have several options when deciding what app to download.