That's normally the number to update the PRL for the Verizon Wireless network. You might have to reboot the iPad more often to allow the SIM card reconnect and refresh the network information.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Due to the age of this thread, it will be locked in order to keep discussions current. If you have the same or a similar question/issue we invite you to start a new thread on the topic.