Remote Phone Best Practices

Modified on Mon, 08 Jul 2019 at 09:18 AM

This guide is designed for users who would like to use a device behind a non-Broadsmart internet connection or sites without a Broadsmart-provided voice gateway appliance.   Broadsmart has outlined items that may need to be addressed by the broadband provider and/or within the onsite network equipment in order for the best VoIP service on a remote phone.


Disclaimer: Broadsmart can guarantee that as long as the data traffic is not being blocked you will be able to make/receive calls from your extension and receive calls from any SCA's (Shared Call Appearance) you have associated with your line, however we cannot guarantee that your call logs/BLF's (Busy Lamp Field) will work appropriately when not behind our equipment. Additionally, when not behind Broadsmart equipment we cannot guarantee audio quality as most home providers/modems/routers do not have QoS (Quality of Service) guarantee's and internet speed and latency play a very large role in the quality of VoIP service.


1.  Disable SIP ALG (SIP Application Level Gateway) and/or SIP Transformations

SIP ALG is a feature that sometimes prevents our traffic from flowing properly. SIP ALG can cause various issues, such as a loss of connection with the service, calls disconnecting, or no audio from the beginning of a call.  User’s broadband provider should be able to disable this within the broadband modem and/router. 


2.    Disable any and all VoIP-specific functions

Networking equipment will often come customized for that broadband carrier’s own VoIP specifications (if any).  However, in many situations these customization's can interfere with the Broadsmart VoIP Phone. Ultimately, our system does not require specific VoIP-supporting functions within a customer’s modem and/or router. This goes hand-in-hand with disabling SIP ALG.


3.    Disable SPI (Stateful Packet Inspection) or DoS protection

SPI/DoS protection allows the router to approve or deny any information packets that flow through it for security reasons. However, it often incorrectly identifies Broadsmart VoIP traffic as a security risk. Disabling SPI/DoS will prevent this. DoS protection works by keeping track of how many connections are made to an individual web address and will begin blocking access once a limit is reached. Our phones will all connect to the same site. So, although with a couple phones there may be no problem, the more phones there are, the more likely that the SPI/DoS protection will begin to block the connections. Some routers will allow you to either disable this DoS protection, or increase the limit to allow more connections. 


4.    Allow SIP, UDP, and RTP Protocols

Broadsmart VoIP services use these specific protocols to send and receive traffic. If you are using a firewall to secure any of these protocols, it will interfere with Broadsmart’ s traffic and may inhibit your ability to make or receive calls. The phones should not have any outbound restrictions in place within your firewall and/or router. For more advanced equipment, if your firewall allows you to edit your UDP session timeout, you should ensure that it is set to 30 seconds or more.


5.    Double-NATing (Double-Routing)

Ideally, you will need to have only one device performing routing functions. Double-NATing (double-routing) is known to cause many problems for VoIP phones. It is best to eliminate or bridge any extra or additional routers or modem/router combinations on your network. If you need to put your modem/router combination in bridge mode, please contact your internet service provider (ISP) for assistance. You may also try putting the second router in the first router’s DMZ if bridging is not possible, but this method is not guaranteed to work.


Because Broadsmart’s IP and port range is dynamic, we recommend the phones be allowed open access through your firewall and do not recommend any port forwarding rules. Our phones initiate dynamic connections that eliminate the need to port forward.


These 5 items are Broadsmart’s best practice recommendations for remote VoIP devices.  If you need additional information, please contact our Technical Support Department by submitting a support ticket above or utilizing one of our other contact methods below.



Phone: 800-816-0898 or 954-449-8000

Email: support@broadsmart.com 


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