Google Voice, and ring tones when calling T-Mobile/Sprint numbers

I use Google Voice as my outward-facing number: I place calls via carrier service, but displaying my Google Voice #, and my Google Voice # is the number people call me on.

Recently, something has changed. My SO is on Tello/Sprint (and does not use Google Voice). When I call her phone, I don't currently hear it ring. If I hold on and wait, she'll either answer or I get directed to voicemail, but until either of those happens, it's silent. It's really inconvenient, because I'm not sure the call is actually going through, or Google Voice has failed, or ....

I took the time to investigate last night, with a selection of phones. Results:
When calling from my Google Voice #, installed on a Tello/Sprint phone.:
Tello/Sprint does not ring (but is connected.)
Tello/T-Mobile does not ring, but is connected.
Red Pocket/CDMAS(Sprint) does not ring, but is connected. (So it's not specific to Tello.)
FreeUP AT&T does ring.
Tracfone Verizon does ring.
I repeated the tests using the native cellular number from the Tello/Sprint phone instead of using my Google Voice #. I hear rings for all the outgoing calls above.

I repeated the test using the same Google Voice #, installed on a FreeUP/AT&T phone. Exactly the same results as the list above: so it's not specific to the carrier I'm using to place the calls using my Google Voice #. If I call using my native FreeUP/AT&T number, everything rings. (Same results testing with 2 different underlying carriers for outgoing calls.).

I repeated the test using a different Google Voice #, installed on the Red Pocket/CDMAS phone. The ringing/no ringing results match the first examples, so it's not specific to my usual Google Voice #-- it happens with 2 different Google Voice numbers.

So, this problem seems to be a consistent one when calling from a Google Voice number to either legacy Sprint or T-Mobile lines. My understanding is that the ring tones we hear when waiting for a phone to be answered are 'spoofed' on the calling line, and are created when a particular code is sent from the network handling the receiving end of the call once the circuit switches to the called number are in place.. (I'm not sure about all the details of how this works.) If that's correct, something is broken between Sprint/T-Mobile sending the "connected" code, Google Voice receiving it, and Google Voice "spoofing" the ring tone.

I'm wondering if anyone else is seeing this symptom? I'm also curious if it's similar when calling via VoIP providers in general. (Maybe TextNow? But I only have a semi-functional TextNow line, and haven't had time to test yet.) I'm likewise curious if it's a result of something T-Mobile is doing regarding spam filtering-- but the calls aren't blocked, it's just the missing ring tone.

(Just realized I didn't try calling via my Google Voice # over WiFi. Guess I'll have to gather the phones again...)

I too use GV as my outward facing number and my SO also uses Tello (gsm) without using GV at all. But when I call her with my phone having GV display my GV number, I do hear ringing. So your issue is not happening to me even though I have essentially the same setup.

Thanks, Frasier1! I guess I'm back to trying to figure out what's going on: the same no-ringing situation remains for me, and I've now expanded my testing to include 2 friends on the T-Mobile network with the same no-ring results: one on Mint Mobile, and the other on T-Mobile Postpaid. I've tried everything I can think of other than uninstalling/reinstalling GV. I wonder if it's somehow a regional thing.. the only numbers I know to test with are local.

@KentE Has anything changed on this issue?

No change: the symptoms remain 2 months later. If I call a T-Mobile or Sprint # from my Google Voice #, I don't hear any ringing at all prior to the other line answering (or voicemail picking up). Since my issue hasn't changed, and I've failed to find similar reports elsewhere, I'm kind of stuck thinking that the issue is location based, and might only affect users in a particular T-Mobile routing center.
The problem seems to be consistent to that particular raw combination: It doesn't matter which T-Mo/Sprint MVNO hosts the number I'm calling.. it happens from 2 different GV #'s I can use, and it happens from multiple phones using the same GV # for outgoing calls. If I call the same #s from my native cellular #, I hear it ring.

Do you get the same results using GV over data vs using carrier minutes? Also are you using traditional carrier voice or VOLTE?

Both interesting questions!

I've never used GV over data-- only over carrier minutes.

My primary phones don't have VoLTE: FreeUP/AT&T over 3G voice (.... I know.....), and Tello/Sprint lines. (....I know....). I do have a Tello/T-mo/VoLTE line, and a Tracfone/VZW/VoLTE line at hand:

I'll try both of those permutations in the next few days.

Some of the T-Mobile & Sprint numbers I'm calling are VoLTe capable, and some aren't.