Group messages delayed in receiving

[Scorpio49]

6 days since I moved 2 iPhones over from ATT. Intermittent problems with group messages. The group receives my SMS messages fine however sometimes their responses are not received or if received some may be completely missing.  Today I received 27 messages all at once that somehow were stuck for 12 hours.  This has happened twice in 6 days.  IMessages work fine, SMS group is the problem. SMS individual messages are fine.  Iphone 8plus, up to date software, reconfigured messaging, reset network. Never had this issue with ATT

[DaveO3]

The answer may lie somewhere in the following link:

https://www.verizon.com/support/knowledge-base-207135/

Apparently if you have group messaging enabled in your Messages settings, your group SMS becomes an MMS and therefore requires your (and likely your recipients) cellular data be enabled, and somehow this impacts the process. This may also happen if you have more than 10 recipients?

[Scorpio49]

Group messages on, MMS on, SMS on.  7 days with Xfinity mobile and difficulty receiving group texts. There are 3 people on group. I have IPhone, other 2 have non IPhone. Tried it with WiFi and cellular data on and just WiFi on. Same result. DID NOT have this issue with ATT.  XMmobile support no help. I believe it's a Verizon issue. 

[DaveO3]

Seems to be an XM problem. Probably something to do with their software which is trying to charge us for the data used with MMS, unlike Verizon and AT&T who don't charge for MMS data. XM has an MMS data limit of roughly 600kb which can cause a problem if you include photos. Some carriers will try to compress photos to stay within the limit. 

You may have to resort to email or WhatsApp?

[Scorpio49]

Most of the group messaging back and forth are simple text messages. I do not understand why group messages to me are missing a portion of the thread or why 27 texts were delivered all at one, clogged up for the past 12 hours. 

[DaveO3]

I recall a similar issue last Summer with some users who were traveling internationally and it might have been with MMS. Once one MMS had a problem, then everything was backing up either because of a too large photo (>600kb) or because the user had turned off cellular data to save on exorbitant international data charges. 

Until XM fixes this problem I suggest that your group members stop including photos or only send smaller sized photos since their carrier's size limit may be 1MB?

Good Luck

[Scorpio49]

Thanks for the response. No pictures, etc are being messaged in this small group(3 people). Only small back and forth messages from 3 seniors complaining about stuff.  I have IPhone other 2, non IPhone. Issue is only when they send me texts from group - sporadic - sometimes no issues, sometimes missing pieces of texts or they clog up over several hours and come all at once. 
'I thinks it's a Verizon or tower issue. XM no help. Very elementary trouble shooting. Again thanks.