arduino model: MKR NB 1500 modem model: SARA-R410M rev. 02B-00 modem firmware: 05.08 MKRNB library version: 1.5.1 with the example sketch TestGPRS, the modem will not complete more than one loop unless line 58 is changed from these values: if (nbAccess.begin("") != NB_READY) { .... to these values: if (nbAccess.begin("", false, true) != NB_READY) { .... this occurs in all versions since MKRNB v1.4.0, and appears to be related to fix #55 Mike