Strange splitting of messages when sent over SMS to non-Signal receiver

[jonhoo]

I have:

• [x] searched open and closed issues for duplicates
• [x] read https://github.com/WhisperSystems/Signal-Android/wiki/Submitting-useful-bug-reports

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Bug description

Long messages are being split weirdly when sent from an Android Signal client to a non-Signal iPhone client.

Steps to reproduce

• Send a single, long SMS from Android Signal client to a non-Signal iPhone client

Actual result: Message is split up in non-intuitive places, and sent as multiple separate messages. Expected result: Message should be received as a single, multi-part SMS message.

Screenshots

Device info

Device: Nexus 5X (3532671, N4F26I) Android version: 7.1.1 Signal version: 3.27.1

Link to debug log

Unfortunately I did not think to get a debug log dump right after the messages were sent. If I find another recipient that this error occurs with I will post the log then.

[nribeka]

If you sent long text message to the same receiver does it coming out as multiple text message too?

[jonhoo]

@nribeka I'm not sure I understand the question?

[nribeka]

Sorry it wasn't come out very clear. I mean if you send out long text message using original sms app that comes with the phone or hangout, does it come splitted too on the other side? I'm wondering if it's because the recipient's phone (or app) can't merge the text messages or is it a bug on Signal side.

[jonhoo]

I'll try that too next chance I get. Though I suspect this would be very well known if multi-part Android to iPhone SMS messages were never merged.

[moxie0]

@jonhoo It's a carrier rather than a platform thing. CDMA providers, for instance, don't support multipart (the messages just fragment)

[jonhoo]

@moxie0 Ah, I see. That's a shame. Closing as this is not Signal's fault.

[jonhoo]

Interestingly, the messages that I got from them were merged correctly...