3.1.5 Communication Standards
The PPHR contains name-value pairs. Because it is intended
for use in regions without Internet access, it obviously
cannot depend on that for communications. All
cellphone networks support the GSM protocol, which
supports voice and SMS communications. Therefore,
the basic PPHR communicates via SMS (Fig. 3h). This
is actually another reason to use name-value pairs – for
compactness of the information in SMSs. To save characters
the PPHR will only transmit those entries which
have not already been transmitted (see n(S) flag in the
entry description), and which have not been flagged as
erroneous (see n(paE) flag in the entry description). In
spite of this, there is a significant drawback to the SMS
system; SMSs are defined to be only 159-160 characters
in length, so even excerpts from a PPHR would
often require multiple SMSs for transmission. Some