Looks like this is an issue specific to Freedom Mobile users happening since May 9, 2019. Possibly caused by a software update from Freedom around that time, it appears to affect Google Phone (beta) users with Visual Voicemail enabled.
Background
There is a thread on Google's official support for Pixel Phone, which mentions the same issue about some multiple random processes requesting permission to send an SMS to 45567 on multiple setups:
- Device model: Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL,
- Android version: Pie, Q (beta)
- Process name: com.android.sdm.plugin, Connectivity manager, Oemdmtrigger, com.qualcomm.data, uceShimService, Phone and Messaging St..., Modem Service, SDMService, [etc.]
- Software update: After the May security patch, or after an update to "Carrier Services" and "Actions Services" but before the May security patch.
Temporary fix/workaround
As per Matthew Naugler Klassen's post, the (temporary) fix is to disable Visual Voicemail in Google's Phone app:
- Open Phone app
- Open Settings
- Under Voicemail, disable Visual Voicemail
Additional Remarks
Freedom Mobile seems to aware and has acknowledged the issue, promising to escalate it and deliver the fix as soon as possible.