The SIP standard is open to some interpretation, and some phone manufacturers (or just certain models / firmware versions) struggle with IPR because of how they interpret the SIP standard. If the phone(s) get confused by IPR then they just become inoperable until their next registration interval.
The good news is that we are constantly updating our phone/model database with customizations to allow major phone makes & models to work properly with IPR. Please contact the support team directly (support@telium.io) and we will help add your model(s) to the database.
We are also working with one phone manufacturer directly, and encourage other manufacturers to reach out to discuss how we can include support for their phones if they don’t quite follow the SIP standard as interpreted by the majority of phones.
