Don't forget - you just use the FQDN/DNS name and the xbee (actually the CELL MODULE) will do the IP look up based on the VZ supplies DNS info. For example, in my unit I set the DL value as "ATDLs12.remoteaware.com". I'm not using API mode, but I assume one can write strings via API mode, as things like P#/phone number is just a string of digits.
After all, the carrier (like VZ) loves to provide DNS lookup, because then they gain marketable data on your usage
