Remote XSTIM Phones - Router Interop Issues

1.0 Background

While standard VoIP technology allows user devices to be connected to telephony systems from anywhere where they have an internet connection. Most VoIP phones do this with SIP protocol, which often then requires special configuration on either the remote site or the customer's main site router to allow the connection to pass through firewalls, SIP ALGs, and NAT. However, E-MetroTel's use of its' XSTIM protocol, in almost all cases allows remote phones to be connected to the main UCX system with no special configuration at either end of the call. This is true for both remote work-from-home scenarios behind a normal residential router and internet connection, or for deployment of a UCX Cloud solution where the entire office location can be considered a remote location connected to through the customer business router/firewall and internet connection.

In some rare cases, however, the capabilities of the remote routers provided by the Internet Service Provider (ISP) have been configured in a way that impacts E-MetroTel XSTIM phones and devices from either connecting or remaining connected to the UCX software. There may be specific service offerings or other intended reasons that require the ISP configuration, and the customer may have specific reasons for choosing the ISP they use. Although we are not able to guarantee that the suggested alternative(s) will not face the same or different issues, this document describes some solutions that have been known to resolve specific customer issues in establishing a working, reliable connection from the remote site to the UCX software location.

1.1 Business Router for Eastlink ISP service

E-MetroTel has worked with a reseller who encountered issues with on of the standard routers provided by Eastlink, an ISP providing services to customers across Canadian regions. In this scenario, the remote users were at a business location and attempting to connect to their UCX Cloud system. The symptom experienced by the customer was that the customer router would lose packets causing XSTIM and Nortel phones to periodically lose their connection to the UCX. To resolve this, the customer and reseller worked directly with Eastlink and replaced their existing router with one of Eastlink's business class routers, specifically the Hitron 3D200 EasyConnect (Model CODA-4582).

1.2 Comcast (Xfinity) Modem/Router

The standard modem/router used for residential internet cable connectivity by Comcast, a large national US based ISP, has been noted in multiple scenarios of allowing the XSTIM phones to connect as expected with no special configuration required. However, it regularly (hourly) drops any existing speech path between the phone and the UCX. To overcome this, there are two alternatives, either replacing the entire modem/router with a customer-provided modem/router or placing the router component into a bridged mode (see below) and continuing to make use of the Comcast modem for physical connectivity to their network.

1.2.1 Replace the Comcast (Xfinity) Modem/Router

Comcast offers advise on using approved third party equipment for connecting to the service and its potential impact on their overall service offering in their support portal webpage. E-MetroTel recommends that our resellers and their customers review this before selecting an alternative modem/router.

1.2.2 Activate Bridged Mode on Comcast (Xfinity) Modem/Router

By activating Bridge Mode on the Comcast supplied modem/router, the customer is able to provide their own router to handle the IP connectivity to the Internet while continuing to use the Comcast cable modem for physical layer connectivity. Note, however, that this can impact other services that may be provided by Comcast such as their xFi and xFi pods. The process for configuring bridge mode on their modem/routers is discussed on the Xfinity Forums site.

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Remote XSTIM
Bridge Mode