Everyone knows that after Scipio Africanus landed on the Carthaginian homeland, the Senate recalled Hannibal from Italy. However despite some Googling I can't find how exactly was this done. Did they use messager pigeons? Or a courier crossing the Mediterranean and then looking for Hannibal on horseback? I can't imagine that it would have been an easy or quick task to deliver a message back in those times.
They sent couriers by boat. The only ancient source that describes this (as far as I can recall) is Livius (XXX, 19).
Livius writes:
Mago proximae silentio noctis profectus quantum pati uiae per uolnus poterat itineribus extentis ad mare in Ligures Ingaunos peruenit. ibi eum legati ab Carthagine paucis ante diebus in sinum Gallicum adpulsis nauibus adierunt, iubentes primo quoque tempore in Africam traicere; id et fratrem eius Hannibalem—nam ad eum quoque isse legatos eadem iubentes—facturum; non in eo esse Carthaginiensium res ut Galliam atque Italiam armis obtineant.
"Mago withdrew during the night and marching as rapidly as his wound would allow reached that part of the Ligurian coast which is inhabited by the Ingauni^1. [2] Here he was met by the deputation from Carthage which had landed a few days previously at Genua. [3] They informed him that he must sail for Africa at the earliest possible moment; his brother Hannibal, to whom similar instructions had been given, was on the point of doing so. Carthage was not in a position to retain her hold upon Gaul and Italy."
The interesting part is the adpulsis navibus adierunt, it doesn't come through as clearly in the translation here (I shamelessly copied Perseus' version, which translates a bit freely), but it says that they had came to him after they had landed their ships (adpulsis navibus), and says that envoys or couriers (legatos) had been sent to him as well (Hannibal was in Bruttium at the time), commanding him to do the same. Hannibal and Mago were in contact with Carthage itself throughout the war, probably with ships as well despite growing Roman sea power.
Later, Hasdrubal the admiral would be sent to escort Hannibal safely back to Africa.
an associated question -- have we yet ever recovered any Punic records and histories? i remember at one time the Carthaginians were considered to have left remarkably little, but it seemed too great a conceit to imagine they did not have a robust literary tradition of their own that we were simply ignorant of.
As a followup question, since this thread got me wondering - how did the Romans train messenger pigeons to find people who moved around?