Verizon Modem (-N3) not answering inbound Circuit Switched Data (CSD) calls

If you are using Verizon modem with version 3.24K firmware the modem will not answer inbound Circuit Switched Data (CSD) calls.

This resolution only applies to Verizon firmware version 3.24K.

To resolve this issue the Verizon modem firmware must be changed to version 3.03K using Wavecom WPST.

To resolve this issue please create a support case, indicate the model number and serial number of your modem, and indicate the response of the modem to the command ATI3.

Support staff will provide you access to the appropriate firmware file and WPST software to resolve this issue.

If having issues with answering of circuit switched data calls with any other CDMA device or CDMA firmware version other than 3.24K below are possible issues:

1. Lack of DTR signal from DTE. In lieu of DTR the command AT&D0 has not been set. Without DTR or without command AT&D0 indicating to ignore lack of DTR the modem will not answer calls.

2. ATS0 value is set to 0 which indicates modem should not answer

3. Lack of CSD service on the cellular account. Most networks are phasing out CSD service so verify this cellular device account has CSD service active.

4. Lack or issue with CSD service at the location where modem is located. Even though other cell phones may work at the same location, the local network may not have CSD capability, or may have capability but issues with equipment preventing CSD from functioning properly.