"Dirty" numbers on T-Mobile MVNOs?

I've used a fair number of MVNO's over the last few years. I use Google Voice for my contact number, and frequently just get a new number for what I anticipate will be a temporary line. (Temporary meaning I'll only be with that MVNO for a few months....)

Generally, this hasn't caused problems for me. Recently, we've had our first experiences with T-Mo MVNOs-- 2 on Mint Mobile, one on Simple Mobile.

The experience with MVNO-assigned numbers on these has not been good. 2 of the 3 numbers have been nearly toxic. I get a lot of spam calls, and legitimate out-of-date-contact calls. (The latter being 'real' phone calls for the last owner of the number.)

I'm curious if others have had similar experience with T-Mo MVNOs. I've read that T-Mo may be far quicker to recycle phone numbers than other carriers, which would explain the high incidence of calls for the old owner, and possibly some of the spam calls. (Figuring that all numbers get on spam lists, but an inactive number sitting in the carrier pool may be cleansed from the telemarketers list if they return number-not-active responses for a while.

This was particularly annoying with MINT, since they have a policy of not replacing a number for any reason. (I'll note that my second MINT line had only a few similar issues, though.)

My new pix wireless phone gets 4 or more spam calls everyday. It is no problem since I can block calls (not possible on my old tracfone,) and I am moving towards giving everyone my google voice number so I can just ignore the calls that come in over the new pix wireless number

Experienced that with Mint and Metro Generated numbers.

I experienced similar when I moved a dumb phone from R+ to Tello and got a new number from Tello. Although, I used the phone with GV for incoming calls, when I would call out it would actually list my Tello number and the somewhat unique name of a female I know not of, and I would occasionally receive calls presumably directed toward her. After about a year, her name was no longer shown to whoever received calls from my phone. I actually used this to my advantage a few times in a good way.

I've changed my number several times with Sprint postpaid and EVERY time the new number has been "dirty" (some dirtier than others).

The "cleanest" numbers I've had were originally from Freedompop.

I do have a few numbers I could port in when switching providers, but not without some consequences. (For example, I have a Tello glovebox PayGo line, but I'd lose the balance.)

As st3fx points out, one of the nice things about most Sprint-network providers is that if a new number is horribly dirty, I can make the decision to port another number over the top of the dirty number-- or request a new random number (and at least roll the dice again.) It's not so easy with GSM providers.

@st3fx Agreed! FreedomPop has always provided me clean numbers (no SPAM calls and maybe just the occasional I have the wrong number). Maybe I was lucky. As a result, I have kept most of them via ports and the remaining two numbers we have with them (used to be more prior to the discovery of RingPlus and their forums).

Same here freedompop numbers are great. And they let you port them out and get a new one without the account closing. And you have some choice on what number you get. So easily the best way to get a number.

@KentE I have ported in numbers to replace existing numbers with AT&T and T-Mobile (both postpaid and prepaid) without needing new SIM cards, so whatever porting limitations are imposed by GSM MVNOs are probably not due to technical constraints at the carrier-level. If the MVNO requires a new activation, perhaps they may be willing to transfer balance from old account.

I am curious if @LiterallyUnlimited has any feedback about this, since Ting is also a GSM MVNO (T-Mobile).

@st3fx I just noticed this on Ting's website listing for their GSM Sim:
"Please note our GSM sim card is a one and done scenario, if you decide to change your number, you will need to purchase a new one."

I'm interpreting that to mean that Ting would work with you to allow a number change on a line, but you'd need to purchase a new SIM. (The SIMs can be picked up for $1 at the moment, now.)
At least that's major advantage over Mint's policy of not allowing number changes at all.

I thought it worked this way with all GSM providers, so I'm glad to hear that your experience indicates otherwise. (Maybe it's one of those special features reserved for the mothership carrier?)

@KentE Thanks. I also see the following:

Ting: How to change your phone number

"You cannot change your phone number on GSM. Unlike CDMA, deactivating and reactivating the SIM is not an option because your GSM SIM card is good for one-time use. Please contact us and we can change your phone number."

One interpretation of the above is that the procedure given for changing a phone number on Ting CDMA involves deactivating and reactivating via online dashboard, whereas, once a GSM SIM is deactivated, it can not be reactivated with a different number. This is true also at the GSM mothership carriers. However, it may be possible for Ting support to manually change the number without deactivating the SIM, which is how porting over an existing number works at the GSM mothership carriers.

In certain cases, if porting a number from a different area than the assigned number, a temporary number in the same area as the number being ported in may replace the assigned number while the port is pending (This is how porting worked at R+ too).

It's all a bit sticky, but we require a new GSM SIM card kind of by mothership software design. I can say it is technically possible to port a number on top of an existing GSM subscription, but it's a whole can of worms with contingencies that makes it almost not worth it. It really 100% is simpler and easier to require a new SIM card, as they're cheap, comparatively speaking. (Technical explanation: As best I can tell, the numbers (temporary and porting) must be within the same CSA)

As to dirty numbers, the MNOs are way more likely to recycle numbers faster in places where they have limited numbering resources. And any increase you see in spam calls when switching to another carrier is likely coincidence or a result of the previous carrier trying to filter on the network side of things. Some blocking methods are effective, some aren't.