、・・・。
If it's urgent, I can page you... (if that's okay).
Literal
Urgent [if-なら], pager [with-で] can-summon-but-けど...
ポケベル = 'pocket bell,' a wasei-eigo coinage for pager/beeper (1990s-era tech, now largely obsolete). ~なら = 'if it's the case that ~.' 呼び出す = 'to summon, call out'; the potential form 呼び出せる means 'can summon.' The sentence trails off on けど, softening the offer and leaving room for the listener's response ('...if that's alright?').