The Elastix NLX4000 is a 1.5U IP PBX appliance which will support up to 300 phones and up to 120 concurrent calls. The Elastix NLX4000 has 2 open PCIe slots which support a variety of different analog and digital port configurations to support what you want to connect. Choose FXO ports to connect to the PSTN via POTS lines, T1 ports to connect via a T1 or use FXS ports to use analog phones or fax machines with the NLX4000. The NLX4000 features a 500GB 2.5in SATA hard drive in RAID1 running on a 1.86GHz Dual Core processor. With this much power, you can easily handle up to 120 concurrent calls. Of course, you don't pay per concurrent call or per extension on Elastix. Elastix is based on Asterisk (R), an open sourced call handling software. When you purchase an Elastix appliance, you are done! There is no required maintenance, per user fees, or upgrade insurance to purchase. VoIP Supply does recommend the purchase of a support contract to help you with your initial installation and set up of your new Elastix appliance, but there are various support options to choose from to fit your budget and your level of expertise. Voicemail Fax-to-email Support for softphones Web Interface Configuration Call recording Brand Enkiu Manufacturer Elastix Power Source Corded Electric Telephone Type Cordless Is there Caller ID No Multiline Operation Multi-Line Operation Answering System Type Digital