The carrier Verizon and Sprint splits longer sms messages in 160 sized single sms, because they run on the old CDMA2000 Standard.
Thats bad, because PGP SMS handles longer messages, but not many short messages.
Now, PGP SMS lite is in test state to support this too.
Key sharing should work now.
update: ECC SMS, ECC SMS lite, PGP SMS and PGP SMS lite should now support CDMA2000 transmission.