Georgia 900 P25 TG 555 and Asterisk/ASL419762

This information is provided to improve the operating experience and answer a few common questions or concerns. 

News – May 3, 2024


  • The 442.125 antenna has been placed on the tower. 
    • Unfortunately the System Control Module failed.  The repeater is on the W4NOC bench.  SCM  replaced and realigned.
    • Should get it back to Site 7 McDonough about May 11.   
  • A test talk group is operating on the VPS.   
    • You are welcome to make transmission tests on TG555. Just say your call sign and ‘testing’.  For extended testing, you may use this private P25Host or talk group (FAQ 30).


Recommended Operating Procedures


1. Press PTT, wait 1-2 seconds before speaking and wait 1-2 seconds before you un-key.

You never know how a ‘spot’ or a repeater may connect to TG555.  It may be satellite, cellular, or a terrestrial service.  Satellite and cellular will introduce additional latency into the flow of traffic through the reflector. Adjust as necessary based on the latency you experience.    A quick PTT can in some cases cause the first part of your transmission to be lost. Wait a bit before you release the PTT button to ensure the last syllable of your sentence is passed through the reflector.  


2. Soliciting a call.

Call more than once if you want to be heard.  A single call might not be heard or recognized.  I notice this frequently where someone keys up, says something, but I did not pick up what was said.  Please observe proper repeater etiquette for monitoring and directed calls.   If you ‘quick key’ and say your call it may not pass your audio through the reflector (See 1 above).


- Directed call:

A directed call is one where you wish to speak to a specific operator.  Say the call of the person you are trying to reach then say your call (his call – your call).  If you say your call first, then you are calling yourself while using another operator’s call sign. 

Examples where W9KLS calls W4NOC: “W4NOC this is W9KLS”, “W4NOC from W9KLS”, “W4NOC this is W9KLS calling”, “W4NOC W9KLS”.


- Monitoring call:

Use this method when you wish to let others know you are available for a QSO.  Examples: “W4NOC listening”, “W9KLS monitoring”.  Calling CQ on a repeater (or P25 Reflector) is not recommended. 


3. Wait 2-3 seconds between transmissions.

This accommodates the delay and allows another station to join.  The P25 Reflectors operate on a VPS in a data center. Latency is <1.5ms. Delay through the reflector between stations is <1 second ‘P25 Repeater to P25 Repeater’ and about 600ms between ‘two hotspot’ users.  Additional software processes in the conversion from analog through the 419762 to the TG555 adds as much as 1 second. 


4. Analog Asterisk/ASL nodes that connect to the TG555/419762 ASLx P25 Gateway should disconnect when finished.

We don’t want to receive an angry email from the operator of another Asterisk/ASL node.  TG555 is always connected to 419762.

There is a link below to see what if any other Asterisk/ASL nodes are connected to 419762. 


5. Transcoded analog to digital audio can be unreadable if the received signal to the repeater is weak.

If your audio level is hot or signal quality into the repeater is poor, these issues are magnified when transcoded.  Proper adjustment of the audio settings in a P25 radio is also important.  Hot P25 audio may sound slightly distorted to another P25 radio. But to a ‘spot’ or analog user, it will be muffled and distorted to the point it may be unreadable.  P25 repeater users or ‘spot’ users should connect to the parrot (P25 TG10) and listen to your audio. 


6. Internet latency and delay introduced by transcoding can vary.  It requires some practice to get used to it.

Enabling SmartPTT prevents doubling. Using recommendation 1 above is also important.


7. Please identify by voice.

Remember to identify every 10 minutes.  An ‘unidentified transmission’ is considered illegal.  When closing a QSO with an international station, you must sign off by giving both your call sign and that of the foreign station. 


Frequently Asked Questions


1. Why is an incorrect call sign or just numbers displayed?

 If the P25 signal is weak into the repeater, the DMRID may be garbled and incorrectly decoded.  Here is an example.


2. Why is an 'r' shown under the Gateway column?

This sometimes occurs when a P25Gateway disconnects from the reflector. Why? I dunno.

In the example below, seconds and milliseconds of the time stamp 10:54:44  was parsed into the “Target” column and the transmission record is shown under ‘Gateway’ at the moment the radio keyed up and steered the repeater P25Gateway to a different reflector.  The ‘r’ follows. 






2Ø23-Ø9-26 14:54:44.83Ø Transmission started from W4NOC NB


3. Why is my call sign not displayed when connected to the reflector through the ASLx419762 P25 Gateway?

Asterisk/ASL does not know your call sign. So it is not passed through to the P25 Reflector or to P25 radios or hotspots.

The call sign of the Asterisk/ASL node 419762 (W4NOC) will be displayed.


4. Why is the first or last syllable dropped?

Please read Recommended Operating Procedures; 1 and 2.


5. I keyed up, threw out my call, but did not get a reply.

Delay is introduced by the software, hardware and the Internet (VPN, Cellular hotspots, Wi-Fi). 

A 2-3 second key up may not pass audio through the reflector. No one will hear you.   

I have witnessed this while tailing the logs with my XTS2500 on the desk beside me.

Read Recommended Operating Procedures; 1 and 2.


6. Why did the reflector dashboard loose the Last Heard and All Heard data?

The logs rotate at 00:00 UT. The P25 Reflector is running on a Pi 3B+ limiting the ability to store logs.


7. How can I tell what Asterisk/ASL analog nodes are connected to the P25-ASLx419762?

Connected node numbers are not passed through to the ASLx-P25 Gateway. So, it cannot be displayed on the P25 Reflector Dashboard.  Allstarlink Stats for 419762.  Also see Stan’s Supermon (Asterisk-ASL nodes).


8. Why do I hear the call sign or telemetry from an Asterisk/ASL node other than W4NOC?

Telemetry on Asterisk/ASL node 419762 is suppressed and will not propagate to other nodes.

Asterisk/ASL telemetry (CWID, audio announcements, bing and bongs) with exception of an emergency MUST NOT propagate to other nodes!

It is an easy fix and well documented in the allstarlink and dvswitch-server forums.


9. Why can't I connect to P25 TG555?

Using the INTERNET for linking repeaters is not as reliable as you would expect.  We do our best to keep the cellular hotspots at the tower working and the VPN operational. When something fails, we resolve it as quickly as possible.  Using cellular data as the transport medium for analog or digital linking is severely flawed and unreliable.   Cable ISPs are no more reliable than cellular.  I long for the days when we could link repeaters with RF.  But that is not practical and cost prohibitive with TCPIP linking over long distances.   


10. Are you using PI-STAR?

PI-STAR images are outstanding for spots and MMDVM repeaters. The repeaters on this network are Quantars.  The PI-STAR team registers the P25 Talk groups and distributes the P25Host files we all depend on.  The x86 LINUX servers supporting the repeaters are running the Asterisk/ASL2.0.0-6B DEBIAN-BUSTER image and DVSwitch-Server.  The P25 Reflector and ASLx-419762-P25Gateway is a Pi3B+. It is running Asterisk/ASL2.0.0-6B RASPBIAN-BUSTER image and DVSwitch-Server.  The P25 Reflector was compiled on the same Pi3B+ from source available from noStar and the P25 Reflector Dashboard is courtesy of M0VUB.


11. How do I connect to TG555?

Any device with a P25Gateway can connect to TG555; P25 Repeaters a networked P25Gateway, spots, droidstar. 


12. I selected TG 555 with my radio and my local P25Gateway did not connect to TG555.

If you are on one of our P25 repeaters, they Startup on 555 and will respond to TG requests from your radio.  This is not true of all P25 repeaters.  Check your radio programming.  Try a different TG, like 10200 North America. Check Special Modes>P25 and verify the repeater is ‘networked, linkable or has an active P25Gateway’.  Different terms are used to indicate the repeater is capable of passing traffic to a P25 TG.  Some P25 repeaters are not networked or do not have an active P25Gateway.  Speak to the owner of that repeater.


13. How do I change talk groups through 9271375, 9277375?

Programming radios is a lengthy topic.  There are a couple of ways to accomplish this with XTS, XTL radios.  My preference is to create a TG list containing a few talk groups; 555 Ga900p25, 10200 North America, 9999 Unlink, 10 Parrot, etc.  Then make talk groups selectable instead of strapped.  Alternately in this example, you can setup 4 channels on 9271375; one channel strapped 555, another strapped 10200, another strapped 9999, another strapped 10. I guess you could have 20 channels on the same frequency, each with a different strapped TG from your TGlist.    Although this video was aimed at programming a Motorola radio to implement talk group connections to a pi-star/mmdvm radio modem, it is the same for repeater frequencies.  If you still have questions, call out on the one of our repeaters and ask for help.  Most every user on this network is familiar with programming XTL, XTS and APX.  I would add one suggestion not covered in the video.  Under “Display & Menu” “Advanced” tab, enable Talkgroup “Display On PTT” and “Display On Receive”. 


14. Is it OK to use talk groups other than 555 through 9271375 or 9277375?

Yes.  The P25Gateways on these repeaters are active and will accept TG requests from your radio.  If you do link to 10200 or another talk group, please select 555 on your radio when you are finished with 10200, key up once and that will reconnect the repeater P25Gateway to 555.  The P25Gateway should timeout after 10 minutes of inactivity on the other TG (such as 10200) and reconnect to the assigned Startup, 555. 


15. Is there a P25Reflector (Talk Group ID) for local traffic or station-to-station through your repeaters?

Station to station traffic always works.  The P25Gateways associated with our repeaters by default connect to 555.  They may be temporarily disconnected from any talk group or they may be connected temporarily by a user to other talk groups such as 10200 North America.  This provides users the opportunity to reach out to P25 talk groups world wide.  The repeater P25Gateways should and usually do revert to 555 after 10 minutes of inactivity on the other talk group (10200, 3166, other).   TG555 is handling the traffic well.  We do not see a need to build a new P25 Reflector at this time.  But a multiprotocol reflector is a possibility.  


16. Are nets permitted on this reflector?

Yes, weekly, bi-weekly, monthly is fine.  Go here to coordinate a net on TG555 or other repeaters in this network and discuss it with Stan.  Monday and Friday evenings are not available at this time.            


17. I don’t have a P25 radio or a spot at this time.  How can I connect to the reflector to experiment with P25?

A frequent member of the TG555 group KD8VHU told us about DroidStar.  Great tip! It is the absolute easiest way to use your Android device to connect to TG555 and experience P25.  The audio we hear over the P25 repeaters from DroidStar Android users is very good.  It is a great way to try P25 before you buy.   


18. What is the best radio ‘spot’ to buy or build?

If you are building it yourself, the pi-star/mmdvm hat/radio modem.  All you need is a Pi, simplex MMDVM Hat (radio modem) and of course a digital radio (P25 or Yaesu C4FM).  I built my homebrew pi-star spot for about $70 with a used Pi (1) B+ from eBay and a MMDVM hat from Amazon ($23 right now).  There are several commercial products on the market including ‘ready to use’ Pi-star/MMDVM_Hat models in a nice case.     Here is a picture of a simple homebrew spot and a video.  A video of the same homebrew spot with a fan.


19. I’ve tried P25 with my ‘spot’ or DroidStar and I’m ready to buy a P25 radio.  How do I select a radio?

Research and ask questions before you buy.  We have operators using Motorola XTL, XTS, APX and Astro Digital Spectra.  Consult batlabs, repeaterbuilder, or radioreference for information.  Look up the model number of the radio, get the flashcode and de-code it to make sure it can operate P25.  Motorola XTL or XTS radios may have a ‘conventional only’ flashcode even though advertised as P25.  Consider how you will program the radio.  You will a need programming cable and the programming software.      


20. Do all repeaters in this network operate P25?

The 927.1375 and 927.7375 are operating P25 and analog (mixed mode).  Both are ‘networked’ and have working P25Gateways.  442.125 is a P25 repeater but not yet ‘networked’ to a P25Gateway.  By 1Q-2023 all three repeaters will operate P25 with functioning P25Gateways.   146.715 is analog but may be connected to the TG555 over the TG555/Asterisk/ASL419762 bridge. 


21. I have a question about Raspberrry Pi?

Please reach out to Stan KI4FVI.


22. I have a question about yaesu f u sio n radios and using the MMDVMHost YSF2P25?

Please reach out to Chris K1KC.


23. I have a question about pi-star?

Throw out a question on the reflector.  The collective knowledge of the 555 user group is impressive.  Share what you know and ask questions. 


24. Can my Open Spo t3 (or 4) connect to private/local P25Reflector?

Yes it can.  I can lead you through it but it is best to consult the Help.  Changing TG with your radio through the OSpot is inconsistent.  The use of terms is confusing and incorrect.  Contrary to the ‘Help’, SelCall is not supported by the P25Reflector.  I have no idea what TG9 is used for and the common Parrot TG10 is not used on the ospot.  Instead they picked the UNLINK TGid 9999 to be the Parrot or ‘Local Echo’.  Go figure!    


25. How much cellular data will my spot consume?

On my test trip, I traveled for 7 hours with my pistar based spot connected by Wi-Fi to my cell.  The phone recorded 29Mb data usage and the cellular provider recorded 23.49Mb data usage.  Obviously I did not talk the entire time, but I did use it frequently on that 7 hour trip. 


26. Why did the node I connected to 419762 disconnect automatically?

Beginning February 27th, 2024 the link inactivity timer (rpt.conf) is enabled on 419762.  It will disconnect all nodes after 10 minutes inactivity.  The inactivity warning message will not play.  


27. I cannot connect my Clearnode to some P25 talk groups or to TG555?

You may need to update your P25Host file.  DVSwitch-server which is the basis for this device includes a script to demand updates to the DMRid list and the host files.  Refer to the seller’s documentation to run the DVSwitch Mobile DVSM_Update script.  The P25Host file is a lookup table that points the user selected TG to a domain name and UDP port.  The master P25Hosts is maintained by the PISTAR group.  Your list of registered P25 talk groups should match this list. 


28. What steps can I take to resolve broken or distorted audio; drop-outs, switching talk group, no callsign displayed, garbled?

Pistar based hotspot users should use the pistar-mmdvmcal and monitor the web console for ‘Loss’ and ‘BER’.  Calibrating your portable radio to your particular hotspot MMDVM radio is essential.  Don’t assume that every radio you own will calibrate the same.  The ADF7021 transceivers used in most MMDVM radio boards do not respond well to high power levels from your portable hand held radio.  I have noticed myself that if I use my mobile P25 radio transmitting to the ‘spot’ high BER and Loss occur even with the mobile set to low (16W).  If you receive reports of drop out, garbled, ‘R2D2’ or no callsign displayed, you may wish to check your calibration and power level.  Those connecting to the 555 through repeaters will normally only experience issues when operating in areas where coverage is weak.  But they are the same issues.  On occasion the issue can be associated with the Internet quality at the repeater sites or the VPN between repeater sites.  It may not be a problem with your equipment. 


This example may be due to poor Internet quality, Wi-Fi issues, radio not calibrated to the MMDVM radio board, excessive power from the user’s radio, too far from, or too close to the ‘spot’.  The audio heard by other uses on the reflector during this period was broken, distorted, with drop-outs, and at times no callsign is displayed.  If you would like to see your traffic for a given period, please provide the date and time UTC and an email address. 


M: 2024-01-22 09:14:29.026 P25, received network transmission from ‘call redacted’ to TG 0 (TGID error)

M: 2024-01-22 09:14:31.663 P25, network end of transmission, 2.7 seconds, 17% packet loss (High Packet Loss)

M: 2024-01-22 09:16:46.436 P25, received network transmission from 0 to TG 0  (DMRid/RadioID corrupt, TGID error)

M: 2024-01-22 09:16:49.398 P25, network end of transmission, 3.4 seconds, 16% packet loss

M: 2024-01-22 09:17:05.995 P25, received network transmission from ‘call redacted’ to TG 555

M: 2024-01-22 09:17:08.338 P25, network end of transmission, 2.7 seconds, 7% packet loss


29. Other users on the 555 report hearing carrier and seeing my call, but no audio when I transmit from my Ya e s u radio to my ‘spot’ (YSFtoP25)?

Make sure your radio is set to VW (Voice-Wide).


30. How do I create a private or local talk group in my spot?

That’s a lot to address here.  For DVSwitch-server users (such as clear node or Analog_Reflector) it is easy.  Go to /var/lib/mmdvm and edit (nano) the file private_P25Hosts.txt.  Add for example this tab delimited line: ‘7    41001’.  Then type ‘sudo systemctl restart p25gateway’.  Private or Local P25 Hosts should be limited to the numbers 2-5,7-8.  For PI-STAR users, this describes the procedure.  Some users report their ‘spots’ cannot use private or local talk groups (see question 24).  You may wish to discuss that limitation with the manufacturer.


31. Who registers P25 Talk Groups or Reflectors?

PI-STAR manages the registry and makes the list of reflectors or P25 Hosts available to all P25 Gateways (spots, USRP clients, P25 repeaters, MMDVM repeaters).  Instructions to register a new reflector are found here.


32. My radio is not recognized by the spot when I transmit or my BER is high (>1%)?

Something may be off frequency, WAY OFF.  Frequency error is the root cause of most of these issues.  Use the pistar-mmdvmcal.  Don’t be surprised if your spot or radio is off frequency, or both.  I have seen spots that have >1khz frequency error.  The worst one was the most expensive.  The TCXO used on some MMDVM radio boards (MMDVM_HS_HAT or MMDVM_HS_DUAL) may be inferior.  Portable radios are notoriously off frequency as well. They may worsen as they age.  Don’t be afraid to adjust the offsets in MMDVMHost.  I have a couple of MMDVM hats.  One is spot on, the other has a frequency error of -124Hz. But I can say that both are stable.  Temperature variation inside the enclosure and inferior TCXO definitely affect stability and accuracy.     



1. How is the analog to P25 audio quality?

The answer is ‘pretty good’.  Good quality analog into the repeater will transcode well to P25.  Poor quality or weak signal audio into the repeater can be unreadable when transcoded to P25.  Node 419762 is connected to a repeater node in Grand Rapids and 419762 is cross-linked to TG555.  This example illustrates the conversion from analog to P25.  The audio is provided courtesy Aaron KC8PRG.  


2. Can I improve the P25 audio quality of the XTS2500 under high background noise conditions?

When you are operating in a noisy environment, the NMN6193(B/C) noise canceling microphone will resolve the problem. Thanks to KD8VHU for the recommendation.


Thank you for using Georgia 900 P25 Reflector TG555.







7 April 2024

Suggestions and corrections are appreciated.