I-Calls

[fmon]

I-Calls in the past have been rare in the Suffolk VA Smartnet II system but lately a couple of School Maint users (TG 61648) have used a phone patch with ID 7632xx displayed on my 785D, always a + of the base 63216. My Pro-92 V1 displays 63216, which of course is a base TG for the Motorola scheme.

I noticed that every time this patch is used the frequency displayed on the Pro-92 is 856.4375, which is the lowest freq in the Suffolk system. The only thing I have ever heard on this freq is the code broadcast of the station call sign, which of course my trunking scanners never broadcast. And until recently, Trunker listed this freq with a (c 867.4375), now it's (c v867.4375) indicating of course, voice traffic. This change is since April this year because I have trunker records then which has the c only.

Now with that background, help me out. Are these broadcast off of the trunking system in FM mode, not MO?

I have a 2067 3.25 installed in one car and a 2067 3.28 in another. I changed both of these freqs in the two 2067's to FM and waited until this dude tried to call someone. The phone ringing with the associated ID came up on the BC 785 which stays on all the time, so I grabbed the nearby 92 and headed for the garage, while turning the 92 on and pressing SCAN and locking out the CC. I turned both 2067’s on (pressing SCAN of course). Both 2067’s picked up the same conversation as the 92 and 785. BTW, on the 92, I had programmed line 4 with text for 63216 and that worked, so the trunking system must be in control of this operation.

I’m currently waiting for this activity again, because I have a Pro-2045 standing by tuned and also programmed that freq in my Pro-96 as FM in the bank with the CC's

 

[AZScanner]

Now with that background, help me out. Are these broadcast off of the trunking system in FM mode, not MO?

I’m currently waiting for this activity again, because I have a Pro-2045 standing by tuned and also programmed that freq in my Pro-96 as FM in the bank with the CC's

Mmmmkay, I'll take a stab at this. I could be wrong but AFAIK:

I-calls are part of the trunked system itself and are handled in the control channel data just like all the other traffic. Something has to tell the 2 radios having the conversation where to tune to receive it. Having said that, it could be that this particular frequency is the primary frequency selected by the site controller for i-call traffic. If there's never more than one i-call taking place at one time, they'll always end up there.

Using the setup you described (i.e. a FM channel programmed with the frequency usually used), your PRO-96 will stop on that freq when there's an i-call but you will not see any i-call id's displayed. Of course, if any other TRS traffic overflows to that channel, it will stop on that too - there's no way for the scanner to determine if it's listening to an i-call or not.

One interesting discovery I had back before I got my first trunk tracker was on the old Glendale AZ TRS - the detective talkgroup behaved very similarly to what you describe: 99 times out of 100, if that talkgroup came active it stayed on one particular frequency. I even had it set as the priority channel on my trusty old PRO-2026. 8)

-AZ

 

[fmon]

Thanks AZ,

An I-call was just initiated by the Parks and Rec group. The Pro-96 functioned just as you described. The tuned non-trunked Pro-2045 remained silent, though I just noticed that Trunker logged a new Hex value OxOed for a frequency in the number two spot of 10 freq system with this call. Trunker has never listed this freq or Hex of. The system has always had 856.9375 available, but I don't recall ever hearing anything on it nor does any of my previous Trunker records show this freq or Hex value.

I believe some changes are going on because early this morning I heard what sounded like digital noise at times (not voice, but the rat-rat-rat of digital on a non-digital Pro-2050) which normally scans in ID SEARH mode.

Also, I just programmed 856.9375 into the 2045 and it's noise is pure Mot CC trunking noise, though none of my trunked scanners have the noise and Trunker shows 860.4375 as the current CC for the system—so does each trunked radio.

Maybe I'll seek info from other locals in the Virginia forum and see if they have noticed any doings.

Thanks again.