How Can I Use an Analog Phone with an IP Phone System?

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SIP phones, either physical or software based, offer distinct advantages in a modern communication setup. Not surprisingly they are favored by most users.


Traditional analog phones can't be plugged directly into your IP network since they have analog RJ11 or RJ12 connectors instead of IP ports.


To address this you will need to purchase an ATA Analog Telephony Adaptor. The ATA has both an IP port and RJ11/RJ12 connections. It acts as a bridge between the IP telephony network and the analog phone, converting digital data to analog signal and vice-versa.




ATA Features and Uses


The VoIP features that an analog phone can handle depend on the ATA itself. While most basic functions (call waiting, caller ID etc.) will be supported. But it is important to keep in mind that those functions may need to be operated with dial codes rather than the keys of the phone itself. Therefore advanced users or those dealing with large call volume may require an actual SIP phone. 


An ATA can also be used for connecting other analog devices, like a fax machine or a Door Phone, to your IP network. For a fax machine compatibility the ATA needs to support the T.38 codec.


Not only is a good ATA is cheaper than a basic SIP phone, but some models usually comes with two or even four analog ports for connecting more analog devices, making it an even more economical solution. 


Voip Gateway vs ATA


Types and Advantages of VoIP Gateways


While they perform a similar analog-to-digital telephony conversions and are sometimes referenced for each other, a VoIP Gateway is a more expensive and capable device. Its main advantage, compared to an ATA, is the ability to handle multiple lines and call simultaneously – anything from a few dozens for entry level models and up to thousands for provider grade ones. 


The two most popular types of VoIP Gateways are classified by having FXO or FXS ports (see more information below.) Those equipped with FXS ports connect analog devices (telephones and fax machines) to your IP network while those with FXO ports can plug to traditional phone lines to facilitate PSTN (traditional phone network) connectivity, which enables them to support calling at times when the IP network is down. 


Some gateways offer both ports while others can be extended to include both ports. There are also GSM VoIP Gateways that can bridge cellular-to-VoIP communication and less common VoIP Gateway with PRI/BRI ports for connecting ISDN lines to a VoIP network. Another considerations for choosing a VoIP gateway is compatibility with your existing equipment and services. For example if you need faxing capabilities ensure that the gateway supports the T.38 codec.


Choosing ATA or VoIP Gateway


As with any technology the distinctions are being blurred over time. Whatever you get just depends on your needs. Generally speaking, if you are dealing with just a handful of analog phones, buying several ATAs will probably suffice. However if you have lots of existing traditional telephone wiring (POTS) or analog telephones, need PSTN access for legacy telephony devices, or you you want to have a backup phone service in case of Internet/VoIP outage you may need a VoIP gateway instead. 


While a VoIP gateway can be useful in specific situations it may entail you will need to maintain two systems – an analog and digital one. Since Telebroad and other providers offer software and cloud solutions that can replace or emulate a VoIP gateway functions it might be more economical for you to consider making the full switch to VoIP. 


Network Considerations and Wi-Fi for ATA


Extra Ports and Double NAT Issues


It might be that all Ethernet ports at the location where the ATA is supposed to be plugged in are already taken. Getting a network switch will solve this by giving you extra ports. There are also simpler and cheaper Ethernet splitters, but they can only support speeds of up to 100Mbps. This should be fine for home and small office use but may not be sufficient for some business use.


Most SIP phones have two Ethernet ports. So if you have a nearby SIP phone you can use it as a splitter. Alternatively you can get an ATA with dual Ethernet ports that function like a mini switch. One port will be plugged to an existing Ethernet socket and the other to the device that was previously plugged in this socket. 


Some of these dual-Ethernet ATAs also have a built-in router. For a home or small office use, this can replace your existing router and minimize cable clutter. But for a bigger office with an existing network this can create a conflict called Double NAT where your Internet traffic is resolved by the two different routers. Double NATing can be problematic for VoIP calls. You can solve it by putting the ATA router into a bridge mode. See more information here (the article contains several other router adjustment ideas for better VoIP calls quality.)


ATAs and Wi-Fi


ATAs with built-in Wi-Fi function are not very common since a physical network connection provides a better call quality and is inherently more secure. Some models sold by Poly can be extended to support Wi-Fi with an additional dongle. 


If your analog phone is too far from an IP socket, you can plug in into an ATA that plugs into a Wi-Fi bridge device to connect it to your wireless network.


You can also use a spare Wi-Fi router for this with bridge mode enabled. If it doesn't support bridge mode try upgrading its firmware or install a custom firmware that does supports bridge mode. There are two custom firmware options available DD-WRT and OpenWRT. You must download the exact firmware version for your router, otherwise you may risk making it permanently unusable. 


Never power off the router at any time during a firmware upgrade or installation. Factory reset it before installing a custom firmware or before upgrading on some brands. It is a good idea to backup and take note of the major settings, just in case you cannot restore settings automatically.


Also keep in mind you should change the firmware only if you actually own the router, otherwise you would need to talk with your ISP to see if doing so is permissible. With some ISPs their service will only work with the router's current firmware and configuration! 


Powerline Adaptors


An alternative solution for shortage of IP sockets is plugging the ATA to a powerline adapter that pairs with a powerline adaptor plugged to your router. These provide network connectivity using existing electrical wiring of up to about 1000 feet (that is wire lenght, not absolute distance.) While powerline adaptors can even work across different floors, for optimal performance they should be on the same electrical circuit. This should be the case for a home/small office but not necessarily so for bigger offices. 


FXS and FXO Ports


FXS stands for Foreign Exchange Subscriber. It is a type of analog telephony port that typically, as a wall socket, delivers analog phone signals, call ringing, and electric current from the phone company's exchange office (the PSTN) to the the subscriber. The subscriber is the FXO port Foreign Exchange Office on analog phones or other devices that receives the analog signals from the phone company's exchange office via an FXS socket.


When planning to buy an ATA/Voip Gateway you must take these ports into consideration:


  • If you need to connect analog devices (phone, fax, etc.) to your VoIP network, the ATA/VoIP Gateway need to have FXS ports! The FXS port will deliver analog signals (converted from your VoIP network) to the FXO ports on the analog devices, and vice versa.

  • On the other hand, you would need your Voip Gateway to have an FXO port if you wish to connect your VoIP system to the PSTN, existing copper telephony lines, or a traditional PBX. The FXO port on the VoIP Gateway will receive the analog signals from these sources so the gateway can convert and deliver them to your VoIP network, and vice versa. 

Having both ports allows for a lot of flexibility and lets you keep legacy analog equipment while having PSTN connectivity for your digital system, all without needing an analog infrastructure other than a line that connects to the PSTN. 


Configuring an ATA


Once you connect the ATA/VoIP Gateway to analog devices or lines it still need to be configured to with the relevant server and users settings. With some devices this can be done with auto-provisioning from a web user interface.


If auto-provisioning is not available you would need assign a line to each analog device connected to the ATA's FXS ports. This is done from the Telebroad admin portal. You don't need to assign a ling to the ATA itself. Access the ATA's web user interface and configure it with the IP address of your Telebroad server account and user names/SIP passwords you assigned to the lines. Call one of the lines you assigned. If the analog phone rings you have just successfully configured your ATA.


To access an ATA/VoIP Gateway web user interface you would need to know its IP address. With some devices there is a default address that requires you to connect a PC directly to the Ethernet port (unless if your device supports Wi-Fi or you have connected it to a Wi-Fi bridge, as described above.) With other devices you can dial some access codes on an analog phone connected to the device and use an IVR menu to obtain the IP address. 


Emergency Service Devices


One distinct advantage of traditional phone lines is that they are powered by the nearest telephone switch and can keep working even during a power outage. Your ATA/VoIP, however, will not work when the power is out unless it has a battery backup. Since it can also fail due to Internet outage, you can see why it is not a good idea to use ATA/VoIP Gateway for emergency service devices such as alarms and elevator emergency call buttons.


So while it is technically possible to use an ATA/VoIP Gateway with analog emergency service devices, this is strongly advised against since ATA/VoIP Gateway introduces an extra point of failure that can prevent the emergency device from functioning at the worst time. 


From a legal perspective, fire and building regulations will also most likely make it invalid to use a VoIP setup for emergency service devices. If you are unsure about these regulation in relation to your communication setup you can consult your building operations supervisor, the vendor/service provider of your emergency equipment, or the relevant authorities.

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