Grandstream 42XX Series Making Ghost Calls

[bschoeberl]

I have 16 total Grandstream gateways in our environment.  Many of the ports on these gateways initiate outbound "ghost" calls dialing +11, +12, +122, and so many other combinations but never a complete number.  My company manages retirement communities and we manage about 25% of our resident phones through the Grandstream gateways.  I opened a ticket with Grandstream, but they keep giving me solutions to INBOUND "ghost" calls, which I do not have an issue.  Has anyone seen this in their environment?

[Eliot]

hi @bschoeberl 

Are your GXW42XXV2 gateways version V2?  Do your 42XXV2 devices have firmware 1.0.29.9 installed?  If not, I suggest you install the current Zoom approved firmware.

Zoom Phone Certified Hardware

Out of the 16 gateways, how many experience these “ghost” outbound dialing?  If there are some gateways which do not experience these issues and some that do, check for differences in the gateways, i.e. are some V1 and some V2, some with one firmware version and others with a different version, and some with one model number and others with a different model number.

Are there certain communities experiencing this issue while other communities do not experience this issue?  If so, it may be something to do with the analog wiring from the gateway FXS port to the telephone and or maybe an intermittent power issue.

What do you see in the Zoom Phone Logs?

What make and model of analog telephones are connected to a GXW42XXV2 FXS port?

In addition to opening another ticket with Grandstream, you may want to open a ticket with Zoom.

Some Grandstream Documentation that may be a help:

Datasheet_GXW4200_series_v2_English_june_2022.pdf

GXW42XX V1/GXW42XX V2 Series – User Manual - Documentation Center

Did my response answer your question? If so, please don't forget to mark the reply as an accepted solution.

thanks,  eliot

[bschoeberl]

All gateways are V2 and up to date with firmware 1.0.29.9.  There are three gateways that are the biggest culprit, but mainly three 24-port gateways, model GXW4224V2.  The issue is more prevalent at one location more so than the others.  We have also thought it may have something to do with the wiring from the end location (i.e., phone) from the gateway.  There are three handoffs from the gateway to the endpoints that span about 3 football lengths.  It is a large campus.

The Zoom logs show many calls to +11 and other permutations that always begin with +11.  We are agnostic to the analog phones connected and don't care what the resident has in their apartments.  I opened a ticket with Zoom and they have requested the CDR.  Though the issue is not solved yet, I think we're starting to further isolate the issue.  It is very likely that it is a wiring issue that we never logged on the old Avaya phone system which we replaced with the Grandstream gateways and Zoom as the phone platform.

[Eliot]

hi @bschoeberl 

i think three football fields is about 1,000 feet; grandstream data sheet claims up to 6,000 feet on 24 awg cable.  

hopefully, the cables are at least ANSI/TIA-568-C.2 Category 3 or higher cables with 24 awg or larger diameter (23 awg) wires. 

if the cable runs near electrical power cables, flourescent or led bulbs, and/or large motors, electrical currents could be induced into your voice cables.  The currents (electrical noise) could be causing the ghost dialing.

in addition, if the voice cables are spliced or punched down and cross connected (handoffs?), you could check the splices and cross connects.

You can also check the direct current resistance.  According to a spec sheet for Belding cat 3, 24 awg, the max resistance should be about 93.8 Ohm/km or 28.6 Ohm/1000ft and the max capacitance should be approximately 330 pF/100m.  Different cables will have different specs.

thanks,  eliot